Journal of Thrombosis and Haemostasis, 1: 2239±2259
LETTERS TO THE EDITORS
Screening of high factor VIII levels is not recommended in patients with recently diagnosed pulmonary embolism P . W . K A M P H U I S E N , M . T E N W O L D E , y E . M . G . J A C O B S , E . F . U L L M A N N z and H . R . B UÈ L L E R y Departments of Internal Medicine, Section of Vascular Medicine, University Medical Center Nijmegen; yVascular Medicine, Academic Medical Center, Amsterdam, and zPulmonary Medicine, Rijnstate Hospital, Arnhem, the Netherlands
To cite this article: Kamphuisen PW, Ten Wolde M, Jacobs EMG, Ullmann EF, BuÈller HR. Screening of high factor VIII levels is not recommended in patients with recently diagnosed pulmonary embolism. J Thromb Haemost 2003; 1: 2239±40.
Dear Sir, Factor (F) VIII activity levels 150 IU dL 1 are associated with an increased risk of venous thromboembolism (VTE) [1±3]. It has been shown that 25% of the patients with a ®rst episode of venous thrombosis and 11% of the healthy population have such high FVIII levels [1]. Furthermore, high FVIII levels may increase the risk of recurrent thrombosis [2,4]. Thrombophilia screening of patients with VTE for high FVIII levels may therefore be important. FVIII is an acute-phase reactant and may be elevated due to the thrombotic event. However, high FVIII levels measured in patients with venous thrombosis at least 6 months after the event persist over time and are generally not in¯uenced by acutephase reactions [5,6]. Since thrombophilia screening is often performed shortly after the diagnosis of VTE, i.e. at presentation before the start of anticoagulant therapy, it is unclear whether measurement of FVIII at that time is reliable. In the acute phase of the thrombosis, in¯ammatory reactions can in¯uence the FVIII level, and an elevated FVIII level may merely re¯ect the consequence rather than the cause of thrombosis. We have investigated whether FVIII levels 150 IU dL 1 measured in consecutive patients suspected for pulmonary embolism (PE) were persistent over time, and, by measuring C-reactive protein (CRP) levels, to what extent an acute-phase reaction was associated with high FVIII levels. Patients with objectively con®rmed PE were compared with patients in whom this diagnosis was excluded and who had an uneventful 3-month clinical follow-up. After 3 months, another blood sample was drawn in all patients. FVIII:C levels were measured by a one-stage clotting assay, high sensitivity CRP levels were determined using latex particle-enhanced turbidimetric Correspondence: Dr P. W. Kamphuisen, Department of Internal Medicine, University Medical Center Nijmegen, PO Box 91016500 HB Nijmegen, the Netherlands. Tel.: 31 24 3618819; fax: 31 24 3541734; e-mail: p.kamphuisen@aig. umcn.nl. Received 11 April 2003, accepted 10 May 2003 # 2003 International Society on Thrombosis and Haemostasis
immunoassay (CRP-US; Roche Diagnostics, Almere, the Netherlands) on a Modular Analytics P800 analyzer (Roche Diagnostics). Fifty-one patients with PE and 102 patients with objectively excluded PE were screened. Thirty-one (61%) patients with PE and 41 (40%) of those without PE had FVIII levels 150 IU dL 1; 29 men and 43 women. The mean age was 55 years (range 31±84) for patients and 52 years (22±88) for controls. Twenty-®ve (61%) patients without PE had alternative diagnoses, such as pneumonia, heart failure or malignancy. Initially, mean plasma FVIII levels ( SD) were 197 26 IU dL 1 in PE patients and 194 24 IU dL 1 in patients without PE Three months later, FVIII levels had clearly decreased in both groups compared with the ®rst measurement, with a mean difference of 46 IU dL 1 (95% CI 33±60) for patients with PE and 45 IU dL 1 (29±61) without PE. The mean FVIII concentration was again comparable in the two study groups. CRP levels clearly decreased after 3 months in both PE patients (10.7 9 mg L 1 to 5.0 6.2 mg L 1) and controls (12.4 12.2 mg L 1 to 6.5 5.8 mg L 1), without a difference between these two groups. Table 1 shows that 19 patients (61%) with PE and 22 patients (59%) without PE with initially high FVIII levels had lower levels after 3 months. Consequently, a minority (39%) of patients with PE had persistently elevated FVIII levels 150 IU dL 1. Most (67%) of these patients had idiopathic PE without a concurrent disease. Three patients had chronic obstructive pulmonary disease, four patients had heart failure, two had pneumonia, and three had malignancy. CRP levels were not different between patients with PE and without PE. The overall correlation between FVIII and CRP levels was weak in both groups (0.12 for patients with PE, 0.14 for patients without PE). After 3 months, this association remained virtually the same. These results suggest that screening patients for high FVIII levels at the time of presentation of PE is not recommended, since most of these patients have transient high FVIII levels. Furthermore, CRP is not a reliable parameter to determine whether elevation of the FVIII level is the consequence of an acute phase reaction.
2240 Letters to the editors Table 1 FVIII levels as measured three months after the diagnosis or exclusion of pulmonary embolism in patients with intially FVIII levels 150 IU dL 1
We conclude that a single measurement of the FVIII level at admission for thrombophilia screening should not be advised.
FVIII (IU dL 1)
PE (n 31)
PE± (n 41)
References
< 100 100±125 125±150 150
1 8 10 12
3 11 10 17
1 Koster T, Blann AD, BrieÈt E, Vandenbroucke JP, Rosendaal FR. Role of clotting factor VIII in effect of von Willebrand factor on occurrence of deep-vein thrombosis. Lancet 1995; 345: 152±5. 2 Kraaijenhagen RA, in't Anker PS, Koopman MM, Reitsma PH, Prins MH, van den Ende A, BuÈller HR. High plasma concentration of factor VIIIc is a major risk factor for venous thromboembolism. Thromb Haemost 2000; 83: 5±9. 3 Tsai AW, Cushman M, Rosamond WD, Heckbert SR, Tracy RP, Aleksic N, Folsom AR. Coagulation factors, in¯ammation markers, and venous thromboembolism: the longitudinal investigation of thromboembolism etiology (LITE). Am J Med 2002; 113: 636±42. 4 Kyrle PA, Minar E, Hirschl M, Bialonczyk C, Stain M, Schneider B, Weltermann A, Speiser W, Lechner K, Eichinger S. High plasma levels of factor VIII and the risk of recurrent venous thromboembolism. N Engl J Med 2000; 343: 457±62. 5 O'Donnell J, Tuddenham EG, Manning R, Kemball-Cook G, Johnson D, Laffan M. High prevalence of elevated factor VIII levels in patients referred for thrombophilia screening: role of increased synthesis and relationship to the acute phase reaction. Thromb Haemost 1997; 77: 825±8. 6 Kamphuisen PW, Eikenboom JCJ, Vos HL, Pablo R, Sturk A, Bertina RM, Rosendaal FR. Increased levels of factor VIII and ®brinogen in patients with venous thrombosis are not caused by acute phase reactions. Thromb Haemost 1999; 81: 680±3.
(3%) (26%) (33%) (39%)
(7%) (27%) (24%) (41%)
When FVIII measurement is performed as a screening for thrombophilia, it is necessary to obtain a reliable FVIII level. In 61% of our patients with PE and FVIII levels 150 IU dL 1 at presentation, these FVIII levels clearly decreased 3 months after the event. These subjects would have been misdiagnosed for having sustained high FVIII when a measurement was performed only at presentation. This phenomenon is probably caused by the thrombotic event itself, which may occur up to 6 months after the event [5,6]. Since we selected patients with high FVIII levels and only obtained two samples per patient, it may be that the observations were the result of regression-tothe-mean due to assay variability, in which case the conclusion should not be that a measurement in the acute phase is a poor predictor, but that a single measurement is a poor predictor.
Availability of technology to evaluate for pulmonary embolism in academic emergency departments in the United States A . E . J O N E S and J . A . K L I N E Department of Emergency Medicine, Carolinas Medical Center, Charlotte, NC, USA
To cite this article: Jones AE, Kline JA. Availability of technology to evaluate for pulmonary embolism in academic emergency departments in the United States. J Thromb Haemost 2003; 1: 2240±2.
Dear Sir, The standards in technology required to diagnose and riskstratify pulmonary embolism (PE) continue to evolve. Recent studies have suggested that the use of computed tomography (CT) angiography with indirect phase venography increases the Correspondence: Jeffrey A. Kline, Director, Emergency Medicine Research, Department of Emergency Medicine, Carolinas Medical Center, PO Box 32861, Charlotte, NC 28323-2861, USA. Tel.: 1 704 355 7092; fax: 1 704 355 7047; e-mail:
[email protected]. com Received 14 April 2003, accepted 17 April 2003
sensitivity of the diagnosis of PE [1,2]. Multiple studies have demonstrated the prognostic signi®cance of right ventricular hypokinesis on echocardiography for patients with PE [3±5]. Likewise, communications have suggested that elevated troponin T or I measurements may increase the odds of an adverse outcome from PE [6]. Others have suggested that 12-lead electrocardiography and the pulse oximetry measurement have value in risk-strati®cation of patients with PE [7,8]. A large body of literature has examined the use of the D-dimer assay as a screening test for PE. At our center, one-half of all cases of PE are diagnosed in the emergency department (ED). We submit that the availability of these modalities in the ED setting should be considered as clinical policy guidelines for PE are developed. # 2003 International Society on Thrombosis and Haemostasis
Letters to the editors 2241 Table 1 Survey responses Positive responses Question
N
%
1. Imaging modality CTA without CTV CTA with CTV VQ scan
32 17 11
54 18 28
2. Diagnostic testingz a. D-Dimer b. Troponin T or I c. 12-lead EKG d. Pulse oximetry e. Vital signs
45 54 60 60 60
75 90 100 100 100
3. Echocardiography availability§ All times All times on weekdays Daytime hours, all days Daytime hours, weekdays Occasionally (< 30% of all times) Almost never (< 10% of all times
3 2 2 27 9 17
5 3 3 45 15 29
4. PE diagnoses per yearô 0 1±2 2±5 5±10 >10
0 1 18 28 13
0 2 30 47 21
Interobserver agreementy % 73
77 80 100 100 100 23
33
Number (N) and percentage of 60 respondents who responded affirmatively to the question. yPercentage of centers where both respondents had the same answer to the question. Questions 1, 3, and 4 had only one answer, whereas question 2 asked five subquestions. zTests available within 2 h at all times on all days. §TTE available within 2 h at times shown. ôNumber of cases of PE diagnosed by each respondent per year. CTA, Computed tomography angiography; CTV, computed tomography venography; VQ, ventilation/perfusion lung scan; ECG, 12-lead electrocardiography; TTE, transthoracic echocardiology.
In December 2002, a survey was sent by electronic mail to two emergency medicine attending physicians, all with more than 2 years of post residency clinical experience at 30 academic tertiary care hospitals. Study sites were hospitals with emergency medicine divisions or departments which have membership in the Society for Academic Emergency Medicine, and have echocardiography laboratories credentialed by the Intersocietal Commission for Accreditation of Echocardiography Laboratories [9]. The centers represented 30 different cities from 13 states and comprise a wide demographic diversity. The survey contained four multiple-choice questions regarding the use of imaging and risk strati®cation techniques used in the ED by the physicians at their respective hospitals. The respondents were asked to complete the survey independently. 1. What primary method do you use to image the lungs for PE (more than 50% of all cases)? & Spiral CT angiography (/± venous ultrasound), & Spiral CT angiography with indirect venography phase, & VQ scan (/± venous ultrasound). 2. Check all the tests for which you would expect to obtain results within 2 h of order, 24 h/7 days 365 days per year? # 2003 International Society on Thrombosis and Haemostasis
a. & D-dimer, b. & Troponin T or I, c. & 12-lead EKG, d. & Pulse oximetry, e. & Vital signs. 3. Which of the following best describes the availability of a cardiologist-interpreted result transthoracic echocardiography at your institution to evaluate for a non-hypotensive patient in the ED with known PE? & Within 2 h, 24 h/day, 7 days/week 365 days/year & Within 2 h, 24 h/day Monday±Friday & Within 2 h during daytime hours 7 days/week & Within 2 h during daytime hours, weekdays only & Within 2 h, occasionally (50 109 L 1 by day 3 and was normal by day 7. The patient suffered no adverse bleeding or ischemic outcomes. Case 2 was a 57-year-old male who presented with recurrent unstable angina and was commenced on intravenous UFH and a tiro®ban infusion (dose as case 1). The platelet count was 210 109 L 1. The patient had ongoing chest pain with evidence of a non-ST elevation myocardial infarction (non-STEMI) which was complicated with ventricular tachycardia. Emergency angiography and angioplasty were performed. The patient received aspirin and clopidogrel together with continuing the tiro®ban infusion. There was excessive bleeding from the femoral puncture site and a large hematoma. A repeat platelet count at 12 h after commencement of the tiro®ban infusion was only 3 109 L 1. The patient received a platelet transfusion of 4 units. Again there was no evidence of heparininduced thrombocytopenia (HITTS) using methods described in case 1. Platelets rose to >50 109 L 1 by day 3 and were normal by day 5. In both cases the acute profound thrombocytopenia was con®rmed to be secondary to tiro®ban by detection of DDABs (Fig. 1) using ¯ow cytometry methods previously described [5]. Brie¯y, 5 109 L 1 platelets were incubated with patient serum and 1 mg mL 1 of tiro®ban before being triple washed. Platelet-
Fig. 1. Identification of tirofiban-dependent platelet antibodies by flow cytometry. In both cases mean platelet fluorescence (MPF) increased significantly in the presence of tirofiban, and in the absence of drug did not differ from AB plasma control. # 2003 International Society on Thrombosis and Haemostasis
bound immunoglobulin was detected by ¯uorescein-labeled antihuman IgG with positive results de®ned as mean platelet ¯uorescence (MPF) intensity twice that of platelets processed identically apart from absence of tiro®ban. In the second case there was absence of prior exposure to tiro®ban. Naturally occurring DDABs have been detected in cases of GPIIb/IIIa inhibitor-induced thrombocytopenia prior to drug exposure and the level of antibody has increased after drug challenge [2,5]. Unfortunately we could not test for pre-existing antibodies. Of greater interest, however, was that the serum of both patients caused platelet activation (Fig. 2). The serotonin release assay (SRA) was used to test for the ability of the tiro®ban-dependent antiplatelet antibodies previously identi®ed in the serum to cause platelet activation. SRA represents the most sensitive and speci®c investigation for detection of antibody-dependent platelet activation in cases of HITTS [7]. Brie¯y, normal donor platelets are incubated with C14-serotonin to allow uptake into the dense granules before patient serum
Fig. 2. Serotonin release assay showing platelet activation in the presence of tirofiban.
2250 Letters to the editors
is added and incubated in the presence or absence of tiro®ban 1 mg mL 1. The serotonin release is calculated by counts measured by a b-counter compared with total activity and is expressed as a percentage release. In case 2 there was a further ischemic event after commencement of tiro®ban and it is not clear whether this was due to platelet activation from DDABs or part of the acute coronary syndrome. Acute profound thrombocytopenia is an uncommon sideeffect of tiro®ban due to DDABs that bind to GPIIb/IIIa, presumably after tiro®ban-induced conformational change. We describe two further cases. Profound thrombocytopenia is usually of short duration, as in our cases, and severe bleeding has been variable [2,8]. However, tiro®ban-dependent platelet antibodies can cause platelet activation and this may be associated with adverse ischemic outcomes in a high-risk group of patients. This requires further investigation. References 1 The EPIC Investigators. Use of a monoclonal antibody directed against the platelet glycoprotein IIb/IIIa receptor in high risk coronary angioplasty. N Engl J Med 1994; 330: 956±61. 2 Brassard JA, Curtis BR, Cooper RA, Ferguson J, Komocsar W, Ehardt M, Kupfer S, Maurath C, Swabb E, Cannon CP, Aster RH. Acute thrombo-
3
4
5
6 7 8
cytopenia in patients treated with the oral glycoprotein IIb/IIIa inhibitors xemilo®ban and oro®ban: evidence of an immune etiology. Thromb Haemost 2002; 88: 892±7. The TARGET Investigators. Comparison of two platelet glycoprotein IIb/IIIa inhibitors, tiro®ban and abciximab, for ischemic events with percutaneous coronary revascularisation. N Engl J Med 2001; 344: 1888±94. Dasgupta H, Blankenship JC, Wood GC, Frey CM, Demko SL, Menapace FJ. Thrombocytopenia complicating treatment with intravenous glycoprotein IIb/IIIa receptor inhibitors: a pooled analysis. Am Heart J 2000; 140: 206±11. Bougie DW, Wilker PR, Wuitschick ED, Curtis BR, Malik M, Levine S, Lind RN, Pereira J, Aster RH. Acute thrombocytopenia after treatment with tiro®ban or epti®batide is associated with antibodies speci®c for ligand-occupied GPIIb/IIIa. Blood 2002; 100: 2071±6. Abrams CS, Cines DB. Platelet glycoprotein GPIIb/IIIa inhibitors and thrombocytopenia: possible link between platelet activation, autoimmunity and thrombosis. Thromb Haemost 2002; 88: 888±9. Chong BH, Burgess J, Ismail F. The clinical usefulness of the platelet aggregation test for the diagnosis of heparin-induced thrombocytopenia. Thromb Haemost 1993; 69: 344±50. Seiffert D, Stern AM, Ebling W, Rossi RJ, Barrett YC, Wynn R, Hollis GF, Bokang H, Kieras CJ, Pedicord DL, Cromley DA, Tsushung AH, Stein RB, Daly RN, Sferruzza A, Pieniaszek HJ, Billheimer JT. Prospective testing for drug dependent antibodies reduces the incidence of thrombocytopenia observed with small molecule glycoprotein IIb/IIIa antagonist roxi®ban: implications for the etiology of thrombocytopenia. Blood 2003; 101: 58±63.
Antibodies to tissue factor pathway inhibitor are uncommonly detected in patients with infection-related antiphospholipid antibodies R . R . F O R A S T I E R O , M . E . M A R T I N U Z Z O , G . D E L A R R A NÄ A G A y and G . J . B R O Z E z
Division of Haematology, Thrombosis and Haemostasis, Favaloro University, Favaloro Foundation; ySection of Biochemistry, Thrombosis and
Haemostasis, Hospital of Infectious Diseases FJ MunÄiz, Buenos Aires, Argentina; and zDivision of Haematology, Washington University, BarnesJewish Hospital, St Louis, USA
To cite this article: Forastiero RR, Martinuzzo ME, De LarranÄaga G, Broze GJ. Antibodies to tissue factor pathway inhibitor are uncommonly detected in patients with infection-related antiphospholipid antibodies. J Thromb Haemost 2003; 1: 2250±1.
Dear Sir, Antiphospholipid antibodies (aPL) have been reported in a variety of clinical conditions [1]. The presence of autoimmune Correspondence: Dr Ricardo R. Forastiero, HematologõÂa, Universidad Favaloro, SolõÂs 453 (C1078AAI) Buenos Aires, Argentina. Tel.: 54 11 43781145; fax: 54 11 43810323; e-mail: forastiero@favaloro. edu.ar Received 19 May 2003, accepted 30 May 2003
aPL associated with vascular thrombosis and/or pregnancy morbidity de®nes the antiphospholipid syndrome (APS) [2]. However, aPL are also commonly found in many acute or chronic infectious diseases. It is now widely accepted that most APS-related aPL do not bind directly to anionic phospholipids, but recognize the phospholipid-binding plasma proteins b2 glycoprotein I (b2GPI) and prothrombin [3]. The distinction, however, between autoimmune-type aPL (APS-associated) and infectious-type aPL has been recently challenged, with the ®ndings that anti-b2GPI and antiprothrombin antibodies are also frequently detected in patients with leprosy [3±5]. # 2003 International Society on Thrombosis and Haemostasis
Letters to the editors 2251 Table 1 Prevalence of anti-TFPI in 90 patients with infectious diseases and with or without antiphospholipid antibodies (lupus anticoagulant and/or anticardiolipin antibodies) Group
aPL
n
anti-TFPI
Normal controls Syphilis
Negative Positive Negative Positive Negative Positive Negative
79 10 10 20 10 26 14
3 1 0 2 0 1 0
HIV Leprosy
anti-TFPI (> 50 U mL 1)
(3.8%) (10.0%)
0 0
(10.0%)
0
(3.8%)
0
Among the plasma protein antigenic targets of aPL, tissue factor pathway inhibitor (TFPI) has been recently described [6]. In a previous report, we demonstrated that autoantibodies to TFPI (anti-TFPI) are commonly found in patients with aPL without infections [7]. Moreover, the presence of high titers of anti-TFPI seems to identify patients with an increased risk of the clinical complications of de®nite APS. In the present study, we evaluated the presence of anti-TFPI in a cohort of 90 patients (median age 41 years; 57 male, 33 female) with different infectious diseases. There were 20 patients with syphilis, 30 with HIV, and 40 with leprosy (36 had the lepromatous and four the borderline type). Fifty-six patients (10 with syphilis, 20 with HIV and 26 with leprosy) had aPL but none had a history of de®nite APS-related clinical features. Among infection-related aPL patients, the 10 subjects with syphilis had anticardiolipin antibodies (aCL) but no lupus anticoagulant (LA), the group with HIV comprised 18 with LA and aCL, one with LA and one with aCL, and the leprosy group included 25 with LA and aCL, and one with LA. Anti-b2GPI and antiprothrombin antibodies were detected in two and four HIV patients with aPL, and in 23 and 15 aPL positive leprosy patients, respectively. No patient from the syphilis group had anti-b2GPI and/or antiprothrombin antibodies. LA was tested according to the ISTH guidelines. aCL (IgG and IgM isotypes) were measured by using a standardized ELISA, and anti-b2GPI and antiprothrombin antibodies by in house ELISAs for IgG and IgM isotypes [8]. Antibodies to TFPI (IgG and IgM isotypes) were detected in patients' sera as recently described [7]. The cut-off values were 18 and 15 U mL 1 for IgG and IgM anti-TFPI, respectively. Table 1 shows the prevalence of positive anti-TFPI results in the different groups of patients with infections. Positive anti-TFPI were found in four out of 56 (7.1%) infection-related aPL patients. This prevalence was not statistically signi®cant
# 2003 International Society on Thrombosis and Haemostasis
different from that found in normal controls (3.8%). None of the aPL(±) patients with infectious diseases had anti-TFPI. Among patients with infections, titers of positive anti-TFPI were as follows: syphilis (32 U mL 1 IgG), HIV (34 U mL 1 IgG and 47 U mL 1 IgM, 23 U mL 1 IgM), leprosy (23 U mL 1 IgM). No patient presented anti-TFPI of high titer (> 50 U mL 1), as previously de®ned [7]. In summary, antibodies to TFPI are not frequently found in sera from patients with infection-related aPL, even in leprosy patients who have high titers of antibodies to b2GPI and prothrombin. Thus, infection-related aPL differ from APSrelated ones with respect to antigen speci®city, possibly re¯ecting distinct pathophysiological signi®cance. Acknowledgements This work was supported by grants from National Fund of Science and Technology (PICT 2000±01 N805±08160), Ministry of Culture and Education, Argentina, and from Public Health Service (R01-HL34462).
References 1 Triplett DA. Antiphospholipid antibodies. Arch Pathol Lab Med 2002; 126: 1424±9. 2 Wilson W, Gharavi A, Koike T, Lockshin M, Branch W, Piette J, Brey R, Derksen R, Harris E, Hughes G, Triplett D, Khamashta M. International consensus statement on preliminary classi®cation criteria for de®nite antiphospholipid syndrome. Report of an International Workshop. Arthritis Rheum 1999; 42: 1309±11. 3 Carreras LO, Forastiero RR, Martinuzzo ME. Which are the best biological markers of the antiphospholipid syndrome? J Autoimmun 2000; 15: 163±72. 4 de LarranÄaga G, Forastiero RR, Martinuzzo ME, Carreras LO, Tsariktsian G, Sturno MM, Alonso BS. High prevalence of antiphospholipid antibodies in leprosy: evaluation of antigen reactivity. Lupus 2000; 9: 594±600. 5 Arvieux J, Renaudineau Y, Mane I, Perraut R, Krilis SA, Youinou P. Distinguishing features of anti-b2 glycoprotein I antibodies between patients with leprosy and the antiphospholipid syndrome. Thromb Haemost 2002; 87: 599±605. 6 Cakir B, Arnett FC, Roubey RAS. Autoantibodies to tissue factor pathway inhibitor (TFPI) are associated with arterial thrombosis/stroke. J Autoimmun 2000; 15: A11(abstract). 7 Forastiero RR, Martinuzzo ME, Broze GJ. High titres of autoantibodies to tissue factor pathway inhibitor are associated with the antiphospholipid syndrome. J Thromb Haemost 2003; 1: 718±24. 8 Forastiero RR, Martinuzzo ME, Cerrato GS, Kordich LC, Carreras LO. Relationship of anti b2 glycoprotein I and anti prothrombin antibodies to thrombosis and pregnancy loss in patients with antiphospholipid antibodies. Thromb Haemost 1997; 78: 1008±14.
2252 Letters to the editors
Warfarin and acenocoumarol dose requirements according to CYP2C9 genotyping in North-Italian patients M . S P R E A F I C O , F . P E Y V A N D I , D . P I Z Z O T T I , M . M O I A and P . M . M A N N U C C I Angelo Bianchi Bonomi, Hemophilia and Thrombosis Center and Fondazione Luigi Villa, IRCCS Maggiore Hospital and University of Milan, Milan, Italy; and Department of Transfusional Medicine Hematology, SIMT S. Paolo Hospital of Milan, Milan, Italy
To cite this article: Sprea®co M, Peyvandi F, Pizzotti D, Moia M, Mannucci PM. Warfarin and acenocoumarol dose requirements according to CYP2C9 genotyping in North-Italian patients. J Thromb Haemost 2003; 1: 2252±3.
Dear Sir, Warfarin is the main coumarin derivative used for the prevention and treatment of thromboembolism. A wide range of warfarin doses is required to maintain the patient's International Normalized Ratio (INR) within the target therapeutic range. This variable response depends on both environmental and genetic features. The more pharmacologically active form of warfarin, the (S)-enantiomer, is predominantly catabolized through 7-hydroxylation of the cytochrome P450 enzyme 2C9 (CYP2C9). Variant alleles of CYP2C9, 2C92 (Arg144Cys) and 2C93 (Ile359Leu), are associated with an impaired metabolism of warfarin in vitro: 2C92 decreases enzymatic activity by 30% [1], 2C93 by 80% [2], and lead to an in vivo reduction of warfarin clearance, increasing its anticoagulant effect [3±7] and decreasing the mean daily dose required to maintain the therapeutic range. Acenocoumarol, another coumarin derivative widely used particularly in Europe, has a half-life approximately 4-fold shorter than warfarin. (S)-acenocoumarol, the more active form, is clinically inactive because of its short half-life (< 2 h) and is metabolized almost exclusively by CYP2C9, that accounts also for approximately 40% of the clearance of the clinically signi®cant (R)-enantiomer. The in¯uence of CYP2C9 variant alleles on the sensitivity to acenocoumarol is less known than that of warfarin, even if recent studies from Spain established a relation between the 2C93 variant allele and requirement of lower doses but no relevant role for the 2C92 allele [8,9]. In this study we analyzed for the ®rst time the correlation between CYP2C9 genotype and dose requirements in a NorthItalian population on acenocoumarol therapy. We have also examined the behavior of patients on warfarin to compare the results in North-Italian patients with those already reported for patients from North and South Italy [3,4]. To this end 125 patients attending the Thrombosis Center on anticoagulant Correspondence: Dr Flora Peyvandi, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Via Pace, 9-20122, Milan, Italy. Tel.: 39 02 5412 5707; fax: 39 02 5410 0125; e-mail: ¯ora.peyvandi@ unimi.it Received 21 May 2003, accepted 30 May 2003
therapy with warfarin and 56 patients attending the Department of Transfusional Medicine/Hematology on anticoagulant therapy with acenocoumarol were evaluated after giving informed consent for DNA analysis. The polymerase chain reaction reactions and endonuclease digestions described by Taube et al. [6] were used for the detection of the 2C92 and 2C93 variant alleles. Patients treated with warfarin and acenocoumarol were divided according to their CYP2C9 genotype as reported in Table 1 and the mean daily doses administered ( SD) to each group of patients were calculated. Allele frequencies for 2C91, 2C92, and 2C93 were 0.78, 0.13 and 0.09, comparable to those previously reported by Scordo et al. [3] in North-Italian patients and by Margaglione et al. [4] in South-Italian patients. In both warfarin and acenocoumarol-treated groups there was a similar distribution of each allele (data not shown). The mean warfarin and acenocoumarol daily doses required by different CYP2C9 genotypes in our and other studied groups are also reported in Table 1. The mean daily dose of warfarin required by our wild-type patients con®rms the data reported by Scordo et al. [3]. The mean daily doses of warfarin (calculated for 23 weeks in the maintenance phase) required by 2C91/ 2 heterozygous, 2C92/2 homozygous and 2C91/ 3 heterozygous patients and by the only 2C93/ 3 homozygote patient were, respectively, 19%, 30%, 42% and 87% lower (P < 0.0001) than those required by wild types. 2C92/ 3 double heterozygous required 51% lower doses of warfarin. For acenocoumarol, the mean daily dose required by 2C91/ 2 heterozygous patients was not statistically different (P 0.163) from that required by wild-type patients, con®rming data previously reported in Spanish [8,9]. Moreover, 2C91/ 3 heterozygous patients and the only 2C93/ 3 homozygote patient required, respectively, 27% and 74% lower (P < 0.0001) doses than the wild types. 2C92/ 3 double heterozygous required 57% lower doses of acenocoumarol. In conclusion, we con®rm in this North-Italian population the reported data on the in¯uence of both 2C92 and 2C93 variant alleles on warfarin dose requirement during the maintenance phase of anticoagulant therapy. We also con®rm that the 2C93 allele is the only one to have an effect on dose requirements in patients on acenocoumarol treatment. Perhaps the choice of this anticoagulant drug in carriers of allele 2C92 would avoid the # 2003 International Society on Thrombosis and Haemostasis
Letters to the editors 2253 Table 1 Mean daily maintenance doses of warfarin and acenocoumarol required by different CYP2C9 genotypes found in this study and other reported studies Sample size Warfarin This study Italy, Scordo (2002) [3]
125 93
Italy, Margaglione (2002) [4]
180
USA, Higashi (2002) [5]
185
UK, Taube (2000) [6]
561
UK, Aithal (1999) [7]
52
Acenocoumarol This study
59
Spain, TassieÁs (2002) [9]
325
CYP2C9 genotypes
1/ 1
5.67 n 75 5.59 n 54 6.7 n 88 5.63 n 127 5.01 n 392 4.68 n 32 1.75 n 36 2.43y n 169
n, Number of patients for each genotype. yData transformed in mg day
1/ 2
2/ 2
4.6 n 26 3.94y n 15 4.88 n 28 4.31 n 107
1.68 n8 2.05y n 90 1
risk of over-anticoagulation with warfarin, with its inherent risk of bleeding complications. References 1 Crespi CL, Miller VP. The R144C change in the CYP2C92 allele alters interaction of the cytochrome P450 with NADPH: cytochrome P450 oxidoreductase. Pharmacogenetics 1997; 7: 203±10. 2 Takanashi K, Tainaka H, Kobayashi K, Yasumori T, Hosakawa M, Chiba K. CYP2C9 Ile359 and Leu359 variants: enzyme kinetic study with seven substrates. Pharmacogenetics 2000; 10: 95±104. 3 Scordo MG, Pengo V, Spina E, Dahl ML, Gusella M, Padrini R. In¯uence of CYP2C9 and CYP2C19 genetic polymorphisms on warfarin maintenance dose and metabolic clearance. Clin Pharmacol Ther 2002; 72: 702±10. 4 Margaglione M, Colaizzo D, D'Andrea G, Brancaccio V, Ciampa A, Grandone E, Di Minno G. Genetic modulation of oral anticoagulation with warfarin. Thromb Haemost 2000; 84: 775±8.
5.2 n 62
3.7 n 10
2/ 3
1/ 3
3.97 n3 2.95y n2
2.8 n4 2.59y n4
3.27 n 16 2.94y n 16
4.07 n4 3.04 n3
2.34 n3 4.09 n6 ±
0.76 n1 1.25y n2 3.8 n 28 1.60 n5 ±
2.57 n1 2.43y n7
0.75 n2 1.77y n 11
1.8 n2
2.7 n 10
3.32 n 18 3.97 n 53
1.27 n8 1.57y n 48
3/ 3
± 0.45 n1 ±
from the reported mg week 1. 5 Higashi MK, Veenstra DL, Kondo LM, Wittkowsky AK Srinouanprachanh SL, Farin FM, Rettie AE. Association between CYP2C9 genetic variants and anticoagulation-related outcomes during warfarin therapy. JAMA 2002; 287: 1690±8. 6 Taube J, Halsall D, Baglin T. In¯uence of cytochrome P-450 CYP2C9 polymorphisms on warfarin sensitivity and risk of overanticoagulation in patients on long-term treatment. Blood 2000; 96: 1816±9. 7 Aithal GP, Day CP, Kesteven PJ, Daly AK. Association of polymorphisms in the cytochrome P4502C9 with warfarin dose requirement and risk of bleeding complications. Lancet 1999; 353: 717±9. 8 Hermida J, Zarza J, Alberca I, Montes R, LoÂpez ML, Molina E, Rocha E. Differential effect of 2C93 and 2C92 variants of cytochrome P-450 CYP2C9 on sensitivity to acenocoumarol. Blood 2002; 99: 4237±9. 9 TaÁssies D, Freire C, Pijoan J, Maragall S, Monteagudo J, Ordinas A, Reverter JC. Pharmacogenetics of acenocoumarol: cytochrome P450 CYP2C9 polymorphisms in¯uence dose requirements and stability of anticoagulation. Haematologica 2002; 87: 1185±91.
Prothrombin G20210A is not prevalent in North India G . G A R E W A L , R . D A S , J . A H L U W A L I A , N . M I T T A L and S . V A R M A Department of Haematology and Department of Internal Medicine, Postgraduate Institute of Medical Education & Research, Chandigarh, India
To cite this article: Garewal G, Das R, Ahluwalia J, Mittal N, Varma S. Prothrombin G20210A is not prevalent in North India. J Thromb Haemost 2003; 1: 2253±4. Correspondence: Professor Gurjeewan Garewal, Head, Department of Haematology, Postgraduate Institute of Medical Education & Research, Chandigarh 160012, India. Tel.: 91 172 747585; fax: 91 172 744401; e-mail:
[email protected] Received 22 May 2003, accepted 30 May 2003 # 2003 International Society on Thrombosis and Haemostasis
Dear Sir, Venous thromboembolism (VTE) is a common problem of increased morbidity and mortality in the Indians and it has been described at various sites such as deep vein thrombosis (DVT) of the legs, cerebral venous thrombosis, Budd±Chiari
2254 Letters to the editors
syndrome, mesenteric vein thrombosis and splenic vein thrombosis [1,2]. The pathogenesis of VTE is multifactorial and complex with interaction of several genetic predispositions as well as acquired circumstantial risk factors. It has been recommended that since more than one genetic determinant of thrombosis may occur in the same patient, the presence of a single prothrombotic state should not deter one from testing for other polymorphisms. The single base substitution (G!A) at position 20210 in the prothrombin gene results in a polymorphism which is associated with elevated plasma prothrombin levels and an approximately 3-fold increase in the risk of VTE [3]. On studying the geographic distribution of PT G20210A in Europeans a marked ethnic difference in the prevalence of the mutation was noted, with the prevalence being higher in Southern Europeans [4]. It has been noted in a pooled analysis of eight case±control studies including 2310 cases and 3204 controls from Europe that the odds ratio (OR) for VTE was 4.9 (95% con®dence interval 4.1, 5.9) for the factor V Leiden (FVL) and 3.8 (3.0, 4.9) for the PT G20210A mutation, but when the two coexisted the OR for VTE in them was increased to 20.0 (11.1, 36.1) [5]. It has been shown that the mutation probably occurred only once after the divergence of Africans from non-Africans and of Caucasoids from Mongoloid subpopulations. Zivelin et al. have shown a single genetic origin for the PT G20210A as well as for the FVL [6]. Since FVL is prevalent in our population, we looked for the PT 20210A mutation in the same population to see if there was any association between the two in causing VTE. A total of 470 DNA samples, which included 134 normal DNA samples with no history of thrombosis and 336 cases of VTE, were screened for the PT G20210A mutation. Genomic DNA was isolated from peripheral blood leukocytes by using proteinase K and phenol/chloroform extraction protocol. Detection of the prothrombin gene was carried out according to the method described by Poort et al. [3]. The ampli®ed product of 345 bp was subjected to digestion with HindIII R.E. The PT G20210A generates a new HindIII restriction site so that two fragments of 322 and 23 bp are obtained. We used a control heterozygous sample obtained from Department of Haematology, CMC Vellore, South India in each run of the polyacrylamide gel. None of the DNA samples tested was found to be either heterozygous or homozygous for PT 20210A. The cases of thrombosis included 128 patients with VTE of the legs, 89 patients with EHPVO, 58 patients with Budd±Chiari syndrome and 61 patients with either arterial or venous stroke. These data indicate that PT 20210A is uncommon in the indigenous population of north India as well as our patients with thromboembolism. The PT G20210A mutation has been shown to be prevalent in Caucasians. Even in them there appears to be an association of
the mutation with geographic location, with higher prevalence in the southern European countries of 3% than in north Europe (1.7%) in the healthy population [4]. Rees et al., on studying 150 DNA samples from India, detected one heterozygous individual in the control group [7]. A small number of cases of PT 20210A have been observed in south India (personal communication). However, in north India it appears to be absent or very rare. There has been a suggestion that the distribution of FVL and PT 20210A is similar since both are prevalent in Caucasians. However, our data highlight that although FVL is detected in our normal population at a frequency of 3.16% [1], the PT 20210A is not seen. We had found a positive association of FVL with cases of DVT as well as cerebral venous thrombosis [1]. Ghosh et al. in a study from western India did not ®nd any individual with PT 20210A on studying 432 patients with VTE [4]. We conclude that PT 20210A is absent or rare in the indigenous population of India, and raise the question whether screening for the mutation in our patients with thrombosis should be done or discontinued. Acknowledgements We gratefully acknowledge Dr A. Shrivastava, Department of Haematology, CMC Vellore, south India for providing the heterozygous positive control DNA sample for the PT G20210A mutation. This work was supported by a grant from the Department of Biotechnology, New Delhi, India. References 1 Garewal G, Das R, Varma S, Chawla Y, Prabhakar S. Heterogeneous distribution of factor V Leiden in patients from north India with venous thromboembolism. J Thromb Haemost 2003; 1: 1329±30. 2 Ghosh K, Shetty S, Madkaikar M, Pawar A, Nair S, Khare A, Pathare JF, Mohanty D. Venous thromboembolism in young patients from western India. Clin Appl Thromb Hemost 2001; 7: 158±65. 3 Poort SR, Rosendaal FR, Reitsma PH, Bertina RM. A common genetic variation in the 30 -untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and an increase in venous thrombosis. Blood 1996; 88: 3698±703. 4 Rosendaal FR, Doggen CJM, Zivelin A, Arruda VR, Aiach M, Siscovick DS, Hillarp A, Watzke HH, Bernardi F, Cumming AM, Preston FE, Reitsma PH. Geographic distribution of the 20210 G to A prothrombin variant. Thromb Haemost 1998; 79: 706±8. 5 Emmerich J, Rosendaal FR, Cattaneo M, Margaglione M, de Stefano V, Cumming T, Arruda V, Hillarp A, Reny J-L. Combined effect of factor V Leiden and prothrombin 20210A on the risk of venous thromboembolism. Thromb Haemost 2001; 86: 809±16. 6 Zivelin A, Rosenberg N, Faier S, Kornbrot N, Peretz H, Mannhalter C, Horellou MH, Seligsohn U. A single genetic origin for the common prothrombotic G20210A polymorphism in the prothrombin gene. Blood 1998; 92: 1119±24. 7 Rees DC, Chapman NH, Webster MT, Guerreiro JF, Rochette J, Clegg JB. Born to clot: the European burden. Br J Haematol 1999; 105: 564±6.
# 2003 International Society on Thrombosis and Haemostasis
Letters to the editors 2255
A different view of `Toc', as I knew him D. GREEN Professor of Medicine, North western University, Chicago, Illinois, USA
To cite this article: Green D. A different view of `Toc', as I knew him. J Thromb Haemost 2003; 1: 2255.
Dear Sir, It is unfortunate that John B. Graham chose to conclude his interesting article on the discovery of factor (F)X with an unwarranted attack on Leandro Tocantins, a founder of modern hematology [1]. Doctor Tocantins was my mentor during medical school, and inspired me to enter the ®eld of hematology. He was a superb clinician and teacher, always gracious, compassionate, and encouraging. He established the Cardeza Foundation for Hematology Research, which trained a multitude of American and international physicians, improving hematology practice throughout the world. Under his guidance, the Cardeza Foundation conducted innovative research in hemostasis, hemoglobinopathies, and leukemia. While Doctor Graham is correct in stating that Doctor Tocantins' theory of the Correspondence: Professor David Green, Department of Medicine, Northwestern University School of Medicine, 345 E Superior St, Chicago, IL 60611, USA. Tel.: 1 312 238 4701; fax: 1 312 238 1815; e-mail: d-green@northwestern. edu Received 9 June 2003, accepted 9 June 2003
origin of hemophilia was incorrect, the data from his laboratory were quite accurate. What was unfortunate was that the hemophilia patient selected for intensive study, NF, had a potent alloantibody to FVIII. At the time, such antibodies were unknown and so the conclusion was that hemophilia resulted from an inhibitor of coagulation. The observations on this patient, coupled with the use of a highly concentrated (38%) sodium citrate solution for blood collection, conspired to mislead Doctor Tocantins. Surely misinterpretation of laboratory data is not unique among clinical investigators. Perhaps the reason that Doctor Tocantins argued for assignment of the Roman numeral X to Stuart factor was because he wished to reserve number VI for a clotting factor antagonist. At any rate, he should be remembered for his achievements in the development of rigorous clotting techniques, and his many other accomplishments including the ®rst marrow transplants for acute leukemia and the establishment of a major hematology training center. Reference 1 Graham JB. Stuart factor: discovery and designation as factor X. J Thromb Haemost 2003; 1: 871±7.
Milder bleeding tendency in Glanzmann's thrombasthenia patients inheriting HPA-1b in the homozygous state K . G H O S H , S . N A I R , B . K U L K A R N I , S . S H E T T Y and D . M O H A N T Y Institute of Immunohaematology (ICMR), KEM Hospital, Parel, Mumbai, India
To cite this article: Ghosh K, Nair S, Kulkarni B, Shetty S, Mohanty D. Milder bleeding tendency in Glanzmann's thrombasthenia patients inheriting HPA-1b in the homozygous state. J Thromb Haemost 2003; 1: 2255±6.
Correspondence: Dr Kanjaksha Ghosh: Deputy Director, Institute of Immunohaematology (ICMR), 13th ¯oor, New Building, KEM Hospital, Parel, Mumbai 400 012, India. Tel.: 91 22 2413 8518//2411 1161; fax 91 22 2413 85 21; e-mail:
[email protected] Received 11 April 2003, accepted 11 April 2003 # 2003 International Society on Thrombosis and Haemostasis
Dear Sir, We have read with interest the paper by Jacquelin et al. [1]. Glanzmann's thrombasthenia is an autosomal recessive disorder of platelet function due to platelet glycoprotein abnormality. Many platelet alloantigen systems are present on the platelet
2256 Letters to the editors
glycoprotein GPIIb and GPIIIa, of which the human platelet antigen 1 (HPA-1) system is important. In this paper the authors have questioned whether coinheritance of HPA1b/1b and Glanzmann's thrombasthenia provided protection against bleeding. We have performed a similar study in 41 cases of Glanzmann's thrombasthenia patients in India [2]. Our study has shown that HPA1b/1b homozygous patients have moderately increased ®brinogen binding and GPIIb-IIIa receptors along with a very mild bleeding tendency. We kept a regular diary in which we noted down the hemoglobin levels of the patients, frequency of transfusion and bleeding manifestations. One of our HPA1b/1b homozygous patients was a female and in spite of her menstrual challenges did not require any transfusions and had hemoglobin of 10 g dL 1. The clinical manifestations in our Glanzmann's thrombasthenia patients in general are not as moderate as the authors have noted, but most of our patients present with a wide range of manifestations varying from mucocutaneous bleeding and epistaxis to life-threatening gastrointestinal bleeding. The distribution of platelet alloantigens in 41 patients with Glanzmann's thrombasthenia and healthy controls showed similar distribution in both groups [3]. Jacquelin et al. have shown a high predominance of the HPA1b/1b genotype in patients with French Gypsy mutation. This may be due to the founder effect [4]. Many of the rare mutations in a given geographic area can be traced to founder effect. It is an accepted anthropological view that the early Gypsy originated in India
and then spread East and to the rest of Europe. Gypsies themselves in their own literature have agreed to this Indian origin of ancestors. A similar pattern of founder effect coupled with strict endogamy was seen in the prevalence of factor V Leiden mutation in Parsis [5], a group of people who are ®re worshippers and whose ancestors migrated from present day Iran to West coast India more than 1000 years ago. References 1 Jacquelin B, Tuleja E, Kunicki TJ, Nurden P, Nurden AT. Analysis of platelet membrane glycoprotein polymorphisms in Glanzmann's thrombasthenia showed the French gypsy mutation in the aIIb gene to be strongly linked to the HPA-1b polymorphism in b3. J Thromb Haemost 2003; 1: 573±5. 2 Ghosh K, Kulkarni B, Nair S, Shetty S, Mohanty D. Human platelet alloantigen polymorphism in Glanzmann's thrombasthenia and its impact on the severity of the disease. Br J Haematol 2002; 119: 348±53. 3 Kulkarni B, Mohanty D, Ghosh K, Pawar A, Khare A. Frequency distribution of antigens in the human platelet antigen-1 system in the western Indian population. Transfusion 2002; 42: 317±20. 4 Gresham D, Morar B, Underhill PA, Passarino G, Lin AA, Wise C, Angelicheva D, Calafell F, Oefner PJ, Shen P, TOurnev I, de Pablo R, Kucinskas V, Perez-Lezaun A, Marushiakova E, Popv V, Kalaydjieva L. Origins and divergence of the Roma (gypsies). Am J Hum Genet 2001; 69: 1314±31. 5 Pawar A, Ghosh K, Shetty S, Colah R, Mohanty D. High frequency of factor V Leiden mutation in ParsisÐa highly endogamous population in India. Thromb Haemost 2000; 83: 965.
Rebuttal to: LMWH vs. LMWH: superior, equivalent or non-inferior? E . R O C H A and A . P L A N EÁ S y
University Clinic of Navarra, Pamplona, Spain; and yClinique Radio-Chirurgicale du Mail, La Rochelle, France
To cite this article: Rocha E, PlaneÁs A. Rebuttal to: LMWH vs. LMWH: superior, equivalent or non-inferior? J Thromb Haemost 2003; 1: 2256±8. See also Bounameaux H, Perrier A. LMWH contra LMWH: superior, equivalent or non-inferior? Reply to a rebuttal. This issue, p. 2259.
Dear Sir, We have read with interest the recent commentary by Bounameaux and Perrier in Journal of Thrombosis and Haemostasis [1] on the article we published in the same issue of the journal
Correspondence: Prof. E. Rocha Hernando, Head of Haematology Service, ClõÂnica Universitaria de Navarra, Avda. PõÂo XII, 36, 31008 Pamplona, Navarra, Spain. Tel.: 34 9 4829 6397; fax 34 9 4829 6500; e-mail:
[email protected] Received 25 March 2003, accepted 22 April 2003
[2], and we ®nd that some of the opinions and/or statements therein are, in our view, quite surprising. Bounameaux and Perrier wonder `How meaningful are the assumptions on acceptable differences between two treatments?'. They believe that `if the rate had, by chance, been 50% in the enoxaparin group, a 10% absolute difference (20% of 50%) would still have been considered acceptable and a new treatment with a rate of VTE of 60% (close to that observed without prophylaxis) would have been declared non-inferior to the accepted control treatment'. It should be taken into account that in previously reported studies where enoxaparin was compared with active control drugs or placebo in the prevention of venous thromboembolism (VTE) after total knee replace# 2003 International Society on Thrombosis and Haemostasis
Letters to the editors 2257
ment (TKR), the incidence of total VTE ranged from 20% to 39% [3±7]. Therefore, it seems exaggerated to expect that, even by chance, the incidence rate would have been 50%, as speculated in their commentary. We could also argue that, more logically, considering previous results, a 20% VTE rate might have occurred in the enoxaparin group and therefore a 4% absolute difference (20% of this 20% VTE rate) would have been considered non-acceptable. In that case, if a VTE incidence rate of 25% had occurred with the new treatment with bemiparin (perfectly likely based on previous results), the experimental treatment would have been declared inferior. As regards the comment that in our study `the observed rate of VTE in the enoxaparin group was higher than that observed in the comparable patients of another recent trial in major knee surgery' [8], it is true that the VTE rate was higher in our trial, but as we have just stated, the incidence of total VTE with enoxaparin in our study is in the range of previously published studies [3±7]. In addition, previous meta-analyses in major knee surgery have shown an incidence of deep vein thrombosis (DVT) with low molecular weight heparins (LMWH) higher than 30% [9,10]. In this sense, our results are consistent with the rates shown in meta-analyses. It is surprising that the authors of the commentary only compare the results of our study to those of a single study that is favorable to their hypothesis, instead of to all published studies or to the meta-analyses mentioned, as would seem logical. Moreover, the incidence of VTE with enoxaparin in the Bauer study [8] cannot be extrapolated to our study, because the enoxaparin dose regimen (30 mg twice daily vs. 40 mg once daily) and the proportion of evaluable venograms (69% vs. 87%, which means that the quality of venograms in our study was very high and a signi®cant number of venographic DVTs could be detected) in the two studies are not comparable. Bounameaux and Perrier say that, `The rather arbitrary de®nition of the equivalence limits should therefore in the future be endorsed by some registration or scienti®c authority, prior to the beginning of the trial'. The choice of a clinically signi®cant difference for a clinical endpoint is far from easy. It seems to be even more dif®cult to assign a clinically signi®cant difference to a main venographic endpoint. In our knowledge, no previous studies or regulatory authorities have de®ned the clinically signi®cant difference (delta) for venographic/gammagraphic or clinical VTE, so our prede®nition of non-inferiority stated in the protocol was made in relative terms as 20% of the events obtained in the control group (relative risk equivalence interval from 0.8 to 1.2). Our delta was selected taking into account the general recommendations of the European Agency for the Evaluation of Medicinal Products (EMEA) for the choice of delta [11]. In Spain, as in any other EU country, the health authorities and ethics committees which monitor suitability of study design and control its conduct, must approve the study before it can be carried out. Our study was submitted to previous approval and subsequent control. In addition, the study had a steering committee, a data safety monitoring board and an ef®cacy committee [2], whose members had adequate scienti®c authority to establish the suitability of the study. # 2003 International Society on Thrombosis and Haemostasis
Later on, the authors of the commentary wonder `How meaningful is testing for equivalence?' and answer themselves `Demonstrating equivalence may be useful if two treatments are likely to have similar ef®cacy but the new treatment is easier to use, has fewer side-effects, or is less costly. These three potential advantages probably do not apply to the present situation'. It seems obvious that the start of prophylaxis after surgery allows for patient admission into the hospital on the very same day of the intervention, instead of the previous day, which in our opinion is clearly bene®cial for the patient and reduces costs. On the other hand, postoperative start of thromboprophylaxis is currently the thromboprophylactic method preferred by anesthesiologists, at least in our setting, to minimize the risk of spinal hematoma. Moreover, a high percentage of orthopedic surgery patients undergo neuraxial anesthesia (94% in our study). Our aim was to demonstrate that bemiparin started 6 h after surgery could be administered with no lack of ef®cacy compared with enoxaparin started before surgery. The postoperative start of bemiparin administration in our study is consistent with the recommendations of the EMEA [12] and the US Food and Drug Administration (FDA) [13] to minimize the risk of spinal hematoma. Thus, the start of prophylaxis with bemiparin after surgery is easier to manage and also less costly. In addition, the risk of spinal hematoma is minimized. Consequently, the aim of our clinical trial could be justi®ed, since `potential advantages of the new treatment, such as ease of use, increased tolerability or decreased costs, can be anticipated', as Bounameaux and Perrier point out in their commentary. It is also stated that `if it is justi®ed only for licensing of the twelfth interchangeable LMWH, it is probably not legitimate'. We totally disagree with this statement. On the one hand, our objective was not to justify the licensing of another LMWH, since bemiparin was licensed in Spain in 1998, and authorized in six countries of the European Union in 2001. On the other hand, as far as we know, this is the ®rst study published on TKR comparing the ef®cacy and safety of two different LMWHs, and only two previous studies have reported this comparison in hip surgery [14,15]. Likewise, this is the ®rst study to compare two administration regimens of LMWHs that differ in the administration times of the ®rst dose in TKR. Moreover, the interchangeability of LMWHs that they claim, based on a recent quotation [16], is not accepted by Nenci in the same publication [17]. There is widespread agreement in the literature regarding the pharmacologic and therapeutic nonequivalence within the class. These agents clearly differ in physicochemical and biological characteristics, particularly molecular weight distribution, half-life and anticoagulant pro®le. Thus, bemiparin has the lowest molecular weight (3600 Da), the longest half-life (5.3 h), and the largest antiFXa : anti-FIIa ratio (8 : 1) of all LMWHs. In addition, statements by the FDA, the World Health Organization, the American College of Chest Physicians, the American College of Cardiology, and the American Heart Association indicate that LMWHs should not be considered interchangeable [18±20].
2258 Letters to the editors
Finally, even if the only reason was the licensing of a new LMWH, we think that would be an absolutely legitimate reason. The alternative would mean accepting the possibility that an action mechanism was patented, which would lead to the widest monopoly. It is fortunate for the development of new drugs that the mechanism of action cannot be patented, against the opinion of the authors of the commentary.
10 11
References 1 Bounameaux H, Perrier A. LMWH contra LMWH: superior, equivalent or non-inferior?. J Thromb Haemost 2003; 1: 414±5. 2 Navarro-Quilis A, Castellet E, Rocha E, Paz-JimeÂnez J, PlaneÁs A. Ef®cacy and safety of bemiparin compared with enoxaparin in the prevention of venous thromboembolism after total knee arthroplasty: a randomized, double-blind clinical trial. J Thromb Haemost 2003; 1: 425±32. 3 Leclerc JR, Geerts WH, Desjardins L, La¯amme GH, L'Esperance B, Demers C, Kassis J, Cruickshank M, Whitman L, Delorme F. Prevention of venous thromboembolism after knee arthroplasty: a randomized, double blind trial comparing enoxaparin with warfarin. Ann Intern Med 1996; 124: 619±26. 4 Fauno P, Suomalainen O, Rehnberg V, Hansen TB, Kroner K, Soimakallio S, Nielsen E. Prophylaxis for the prevention of venous thromboembolism after total knee arthroplasty. J Bone Joint Surg Am 1994; 76A: 1814±8. 5 Fitzgerald RH Jr. Preventing DVT following total knee replacement: a review of recent clinical trials. Orthopedics 1995; 18 (Suppl.): 10±1. 6 Colwell CW, Spiro TE, Trowbridge AA, Stephens JW, Gardiner GA Jr, Ritter MA. Ef®cacy and safety of enoxaparin versus unfractionated heparin for prevention of deep venous thrombosis after elective knee arthroplasty. Enoxaparin Clinical Trial Group. Clin Orthop 1995; 321: 19±27. 7 Leclerc JR, Geerts WH, Desjardins L, Jobin F, Laroche F, Delorme F, Haviernick S, Atkinson S, Bourgouin J. Prevention of venous thromboembolism after major knee surgery: a randomized, double-blind trial comparing a low molecular weight heparin. Ann Intern Med 1996; 124: 619±26. 8 Bauer KA, Eriksson BI, Lassen MR, Turpie AGG. Fondaparinux compared with enoxaparin for the prevention of venous thromboembolism after elective major knee surgery. N Engl J Med 2001; 345: 1305±10. 9 Howard AW, Aaron SD. Low molecular weight heparin decreases proximal and distal deep venous thrombosis following total knee
12
13 14
15
16 17 18 19
20
arthroplasty. A meta-analysis of randomized trials. Thromb Haemost 1998; 79: 902±6. Brookenthal KR, Freedman KB, Lotke PA, Fitzgerald RH, Lonner JH. A meta-analysis of thromboembolic prophylaxis in total knee arthroplasty. J Arthroplasty 2001; 16: 293±300. The European Agency for the Evaluation of Medicinal Products Committee for Proprietary Medicinal Products. Concept paper on the Development of a Committee for Proprietary Medicinal Products (CPMP). Points to Consider on Biostatistical/methodological Issues Arising from Recent CPMP Discussions on Licensing Applications: Choice of Delta. EMEA/CPMP/EWP/2158/99. Available at: http:// www.eudra.org/emea.html. The European Agency for the Evaluation of Medicinal Products. Committee for Proprietary Medicinal Products. Minimum SPC Wording for Unfractionated Heparins and Low Molecular Weight Heparins regarding the Risk of Epidural or Spinal Haematoma agreed by the PhVWP in November, 2000. EMEA/CPMP/PhVWP/4452/00. Available at: http://www.eudra.org/emea.html. Lumpkin MM. FDA public health advisory. Anesthesiology 1998; 88: 27A±28A. PlaneÁs A, Vochelle N, Fagola M, Bellaud M. Comparison of two lowmolecular-weight heparins for the prevention of postoperative venous thromboembolism after total elective hip surgery. Blood Coagul Fibrinolysis 1998; 9: 499±505. PlaneÁs A, Samama MM, Lensing AW, Buller HR, Barre J, Vochelle N, Beau B. Prevention of deep vein thrombosis after hip replacement. Comparison between two low-molecular weight heparins, tinzaparin and enoxaparin. Thromb Haemost 1999; 81: 22±5. Prandoni P. Low-molecular-weight heparins: are they interchangeable? Yes. J Thromb Haemost 2003; 1: 10±1. Nenci GC. Low-molecular-weight heparins: are they interchangeable? No. J Thromb Haemost 2003; 1: 12±3. Nightingale SL. From the Food and Drug Administration. JAMA 1993; 270: 1672. Hirsh J, Warkentin TE, Shaughnessy SG, Anand SS, Halperin JL, Raschke R, Granger C, Ohman EM, Dalen JE. Heparin and low-molecular-weight heparin: Mechanisms of action, pharmacokinetics, dosing, monitoring, ef®cacy, and safety. Chest 2001; 119 (Suppl. 1): 64S±94S. Ryan TJ, Antman EM, Brooks NH, Califf RM, Hillis LD, Hiratzka LF, Rapaport E, Riegel B, Russell RO, Smith EE 3rd, Weaver WD, Gibbons RJ, Alpert JS, Eagle KA, Gardner TJ, Garson A Jr, Gregoratos G, Ryan TJ, Smith SC Jr. 1999 update: ACC/AHA guidelines for the management of patients with acute myocardial infarction. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Acute Myocardial Infarction). J Am Coll Cardiol 1999; 34: 890±911.
# 2003 International Society on Thrombosis and Haemostasis
Letters to the editors 2259
LMWH contra LMWH: superior, equivalent or non-inferior? Reply to a rebuttal H . B O U N A M E A U X and A . P E R R I E R y
Division of Angiology and Hemostasis, Department of Internal Medicine, University Hospital of Geneva, Geneva, Switzerland; and yMedical
Clinic, Department of Internal Medicine, University Hospital of Geneva, Geneva, Switzerland
To cite this article: Bounameaux H, Perrier A. LMWH contra LMWH: superior, equivalent or non-inferior? Reply to a rebuttal. J Thromb Haemost 2003; 1: 2259. See also Rocha E, PlaneÁs A. Rebuttal to: LMWH vs. LMWH: superior, equivalent or non-inferior? This issue, pp. 2256±8.
Dear Sir, The issues raised by Rocha and PlaneÁs in their rebuttal to the editorial [1] that we wrote in conjunction with the publication of their paper [2] are well taken. However, we would like to point out that our editorial was aimed more at putting the speci®c problems of equivalence studies in perspective rather than at criticizing their own trial. Nevertheless, let us brie¯y consider their arguments. We agree that the ®gure of 50% that we chose as a possible rate of venous thromboembolism (VTE) in the control arm was (too) high but this was just an example to draw the attention on the importance of the absolute VTE rate in the controls. Our point is further stressed by the ®gure of 20% chosen by Rocha and PlaneÁs, which is also speculative. We agree that the observed VTE rate in the control arm of the study [2] was in the range of previously published trials but, again, our intention in quoting the results of one particular trial was to stress for the readers of this Journal the importance of the VTE rate observed in the control arm, not to criticize their study results. The quality of the venograms, however, cannot be evaluated on the sole proportion of assessable venograms reported in a given study. Indeed, a high proportion may re¯ect the optimism of the investigators as likely as the quality of the venograms. We agree that there is no universal de®nition of the clinically relevant difference (delta) that should be used for the endpoint chosen in non-inferiority trials. ICH E9 guideline on `Statistical principles for clinical trials' recommends that a non-inferiority delta should be `the largest difference that can be judged as being clinically acceptable [but should be] smaller than differences observed in superiority trials of the active comparator [i.e. a difference that establishes superiority to no treatment]'. Again, our intention was not to criticize the choice made by Correspondence: Prof. H. Bounameaux, Division of Angiology and Hemostasis, University Hospital of Geneva, CH-1211 Geneva 14, Switzerland. Tel.: 41 22 3729292; fax: 41 22 3729299; e-mail: henri.bounameaux@ medecine.unige.ch Received 20 May 2003, accepted 06 June 2003 # 2003 International Society on Thrombosis and Haemostasis
the Rocha and PlaneÁs in their study but (at least try) to explain the issue in question. We strongly believe that a non-inferiority trial is only justi®ed if two treatments are likely to have similar ef®cacy but the new treatment is easier to use, has fewer side-effects, or is less costly. Rocha and PlaneÁs argue that the postoperative start of prophylaxis in the bemiparin regimen is `clearly bene®cial for the patient and reduces costs'. This is an important argument that may be correct but we doubt that the study was designed to really assess that particular point. Indeed, the delta chosen is probably far higher than the difference that can be expected between a regimen with or without preoperative injection. We said in our editorial that, in our view, an equivalence trial would not be legitimate if its only justi®cation was to allow the licensing of the twelfth interchangeable LMWH. Of course, we did not thereby imply that this was the aim of the paper [2]. Nevertheless, Rocha and PlaneÁs strongly disagree also with our general statement. Obviously, they support the view of Nenci, who said that low molecular weight heparins are not interchangeable [3] rather than that of Prandoni, who convinced us that they are, at least in daily clinical life [4]. Finally, contrarily to Rocha and PlaneÁs, we believe that industry should develop conceptually new drugs rather than copy existing ones just for marketing purposes. Indeed, the only difference that can be expected from two regimens aiming at equivalent ef®cacy might be the occurrence of an unexpected adverse effect of the new compound, an ethical issue that should not be overlooked, even in the best interest of the pharmaceutical companies. References 1 Bounameaux H, Perrier A. LMWH contra LMWH. superior, equivalent or non-inferior? J Thromb Haemost 2003; 1: 414±5. 2 Navarro-Quilis A, Castellet E, Rocha E, Paz-JimeÂnez J, PlaneÁs A. Ef®cacy and safety of bemiparin compared with enoxaparin in the prevention of venous thromboembolism after total knee arthroplasty. A randomized, double-blind clinical trial. J Thromb Haemost 2003; 1: 425±32. 3 Nenci GC. Low-molecular-weight heparins: are they interchangeable? No. J Thromb Haemost 2003; 1: 12±3. 4 Prandoni P. Low-molecular-weight heparins: are they interchangeable? Yes. J Thromb Haemost 2003; 1: 10±1.
