Keywords: computerized decision support system, oral anticoagulation. ... The PARMA paper (Mariani et al, 1990) showed that good therapeutic control could be ...
British Journal of Haematology, 1998, 102, 907–909
Review of computerized decision support systems for oral anticoagulation management D. A. F I T Z M AU R I C E , F. D. R. H O BBS , B. C. D E L A N E Y, S. W IL S ON A N D R. M C M A NU S Department of General Practice, Medical School, University of Birmingham, Edgbaston, Birmingham Received 23 March 1998; accepted for publication 1 June 1998
Summary. Computerized decision support systems (CDSS) are available to assist clinicians in the therapeutic management of oral anticoagulation. We report the findings relating to CDSS for oral anticoagulation management of a primary-care-based systematic review which largely focused on near-patient testing. Seven papers were reviewed which covered four different systems. The
methodology of these papers was generally poor, although one randomized controlled trial showed improved therapeutic control associated with computerized management compared with human performance.
Therapeutic monitoring of warfarin therapy requires two key elements to be undertaken if it is to be successful: the measurement of the INR and an interpretation of the result in order to advise on dosage of warfarin and when the next test should be performed. The element of interpretation has traditionally been the consultant haematologist’s role, with primary care physicians expressing concern at their perceived lack of clinical knowledge to undertake this service (Taylor et al, 1993). Computerized decision support systems (CDSS) can be defined as ‘programmes designed to give advice about significance of results and their implications for subsequent patient management’ (Hobbs et al, 1997). The principle underlying the utilization of CDSS within any clinical environment is that a reproducible decision will be made given a certain set of data. Many clinical situations have been investigated to ascertain the utility of CDSS; however, few have demonstrated enduring effect. One area where success has been reported is the field of oral anticoagulation management. The principle advantages to CDSS are deemed to be reproducibility of interpretation within centres, standardization between centres, and ease of performance assessment. If these features are present, CDSS could enable non-specialist clinicians to undertake tasks which have previously been the domain of the specialist. Anticoagulation CDSS has been reported as enabling non-specialist staff to undertake
therapeutic monitoring within hospital clinics, and also to provide accurate data for audit (Hobbs et al, 1997). This paper reports on the literature identified as part of a systematic review which reported on near-patient testing, CDSS and rapid transit systems relevant to or within primary care (Hobbs et al, 1997).
Correspondence: Dr D. A. Fitzmaurice, Department of General Practice, University of Birmingham, Edgbaston, Birmingham B15 2TT. q 1998 Blackwell Science Ltd
Keywords: computerized decision support system, oral anticoagulation.
METHODS As part of a systematic review of near-patient tests in primary care (Hobbs et al, 1997), computer searches were undertaken covering the period 1986–95 using the following literature databases: Medline; BIDS (Bath-ISI-DataService); Science Citation Index; Index to Scientific and Technical Proceedings, Department of Health; EMBASE; GP Lit Data Base, Royal College of General Practitioners; and CINHAL. The key words used for CDSS were: computerized decision support, expert systems, electronic data interchange and computer communication networks; in combination with: family practice, primary (health) care, physicians office and general practice. A comprehensive examination of the bibliographies from all publications identified by the computer searches was carried out in order ensure that all relevant publications were included in the systematic review. These searches were supplemented by hand-searching citations and specialist journals, and questioning experts in the field. All articles relating to CDSS in primary care were assessed in terms of quality of methodology by an internal review panel. Articles which satisfied the methodology criteria were sent to two independent reviewers (one internal
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D. A. Fitzmaurice et al Table I. Papers included for review; details of papers reviewed, listed by computer system.
System
Paper
Methodology score
Hillingdon Hillingdon Hillingdon PARMA Coventry Virginia Hillingdon, Coventry, Charles
Kubie et al (1989) Wyld et al (1988) Wilson & James (1984) Mariani et al (1990) Ryan et al (1989) Carter et al (1988) Poller et al (1993)
0 1 2 1 2 1 4
to the Department of General Practice, and one external) who judged the papers based on a predetermined marking schedule. The four criteria used for this assessment were: independent blind comparison to a reference standard; appropriate sample composition; reference standard performed on all patients; and sufficient method described to permit replication. Each criteria could be marked as adequate, giving 1 mark, or inadequate, giving 0 mark. Thus each article could achieve a maximum of 4 marks. If there was discrepancy between reviewers in terms of the marking schedule, a third reviewer from within the investigating group adjudicated. RESULTS Seven eligible papers were identified on CDSS which concerned oral anticoagulation management. Of these seven papers, three were concerned with the Hillingdon Programme (Kubie et al, 1989; Wyld et al, 1988; Wilson & James, 1984), one with the PARMA programme (Mariani et al, 1990), one with the Coventry programme (Ryan et al, 1989), one with the Virginia programme (Carter et al, 1988), and one compared the Hillingdon, Coventry and Charles anticoagulant clinic manager programmes (Poller et al, 1993). The methodology scores are summarized in Table I. The highest scoring Hillingdon paper (Wilson & James, 1984) reported an improvement in anticoagulation control following the introduction of an automated system to deal with adjustment of warfarin dose (which resulted in more patient visits). The PARMA paper (Mariani et al, 1990) showed that good therapeutic control could be achieved within a secondarycare setting using CDSS, but highlighted the fact that a consistent approach was necessary for multicentre evaluations to take place. This paper also reported the first use of the mean INR, plus or minus one standard deviation, as a method of comparing anticoagulant clinics in different settings. The Coventry paper (Ryan et al, 1989) described an improvement in therapeutic INR control following the introduction of CDSS. It was not possible to ascertain the level of performance before the introduction of CDSS and whether the reported improvement was a true effect or reflected the learning curve associated with the introduction of new technology.
The Virginia paper (Carter et al, 1988) described a programme for predicting warfarin dosage following a loading dose of 30 mg over 3 d. This was essentially a secondary-care study which may have implications for primary-care workers who wish to commence warfarin therapy in the community. The specific programme is unlikely to have widespread applicability because of the equipment requirements. The paper in which three CDSS systems were compared with human performance achieved a methodology score of 4. This highlights the fact that the study attempted a randomized controlled trial to assess the relative merits of three different CDSS systems for warfarin management, and to compare them with human performance. The study was flawed in that one system (Hillingdon) was suspended from randomization during the study because of poor performance. Nevertheless, it demonstrated that improvements in therapeutic INR control can be achieved by the use of CDSS, particularly as the target INR increases. DISCUSSION This study has shown that there is a paucity of good-quality research available in the field of CDSS for oral anticoagulation, particularly in primary care. Only one of the seven papers reviewed achieved a maximum methodology score. There is evidence from this study, however, that CDSS can achieve improved therapeutic control in terms of INR, when compared with human performance. Since the publication of the systematic review there have been several other published studies which add to this body of evidence. One study is a primary-care-based evaluation of the Coventry system (Fitzmaurice et al, 1996), reporting a significant improvement in patient control, compared with previous hospital-based management. This study has been extended to include the evaluation of CDSS alongside nearpatient testing for INR measurement in primary care. According to Buchanan (1988), expert systems should: provide a solution at the same level of performance as a human expert; employ symbolic reasoning rather than numeric and algorithmic procedures; store knowledge separately from inference procedures; and provide explanations of their reasoning. In general terms, two main types of expert system are available: rule-based systems, where operations are performed subject to a set of rules obtained
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CDSS for Anticoagulation Management from a single or group of specialists in a given field; and probabilistic systems where evidence is weighed and then the best option calculated according to Bayes Theorem (Lundsgaarde, 1987). Anticoagulation systems are also essentially of two further types, being concerned either primarily with initiation of warfarin therapy (Sun & Chang, 1995; Svec et al, 1985) or with maintenance therapy (Wilson & James, 1984; Mariani et al, 1990; Ryan et al, 1989). Initiation modules tend to use Bayesian predictions allied with pharmacodynamic modelling. Although there is some evidence of their effectiveness in reducing the time taken to achieve steady-state warfarin dosage, these modules have not been widely adopted into routine practice. One system which combines initiation with longer-term monitoring has been evaluated (Vadher et al, 1997). In this study, patients were randomized to either conventional treatment or management using the CDSS. Over 70 patients were recruited to each group, with intervention patients achieving steady-state warfarin dose significantly quicker (7 d v 9 d, P ¼ 0·01) and also spending a greater period of time within therapeutic range (64% v 51%). The study of Poller et al (1993), which compared three systems with traditional dosing showed that computer dosing was comparable to traditional dosing at a lower intensity of anticoagulation but performed significantly better (in two systems) at higher intensity. No information was reported, however, regarding patient outcomes in terms of haemorrhagic or thrombotic episodes. The use of CDSS could remove some of the obstacles to primary-care oral anticoagulation management expressed by GPs (Taylor et al, 1993). In particular, the routine use of CDSS would remove the need for specialist training in anticoagulation, enable other health-care professionals to manage clinics (for example pharmacists, laboratory technicians, practice nurses), and provide a consistent management approach. An inherent facility of CDSS for audit would enable performance review and therefore help to ensure maintenance of clinical standards. However, the possible advantages of CDSS in terms of reduction in medical and secretarial time and the availability of automatic audit facilities have not yet been the subject of a publication. It remains important that any new CDSS is subject to full performance evaluation, particularly in the field in which it is intended to be used.
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REFERENCES Buchanan, B.G. & Smith, R.G. (1988) Fundamentals of expert systems. Annual Review of Computer Science, 3, 23–58. Carter, B.L., Barr, W., Rock, W. & Taylor, J.W. (1988) Warfarin dosage predictions assisted by the analog computer. Therapeutic Drug Monitoring, 10, 69–73. Fitzmaurice, D.A., Hobbs, F.D.R., Murray, E.T., Bradley, C.P. & Holder, R. (1996) Evaluation of computerized decision support for oral anticoagulation management based in primary care. British Journal of General Practice, 46, 533–535. Hobbs, F.D.R., Delaney, B.C., Fitzmaurice, D.A., Wilson, S., Hyde, C.J., Thorpe, G.H., Earl-Slater, A.S.M., Jowett, S.M. & Tobias, R.S. (1997) A review of near patient testing in primary care. Health Technology Assessment, 1, No. 5. Kubie, A., James, A.H., Timms, J. & Britt, R.P. (1989) Experience with a computer-assisted anticoagulant clinic. Clinical and Laboratory Haematology, 11, 385–391. Lundsgaarde, H. (1987) Evaluating medical expert systems. Social Science and Medicine, 24, 805–819. Mariani, G., Manotti, C. & Dettori, A.G. (1990) A computerized regulation of dosage in oral anticoagulant therapy. Research in Clinic and Laboratory, 20, 119–125. Poller, L., Wright, D. & Rowlands, J. (1993) Prospective comparative study of computer programs used for management of warfarin. Journal of Clinical Pathology, 46, 299–303. Ryan, P.J., Gilbert, M. & Rose, P.E. (1989) Computer control of anticoagulant dose for therapeutic management. British Medical Journal, 299, 1207–1209. Sun, J. & Chang, M.W. (1995) Initialisation of warfarin dosages using computer modelling. Archives of Physical Medicine and Rehabilitation, 76, 453–456. Svec, J.M., Coleman, R.W., Mungall, D.R. & Ludden, T.M. (1985) Bayesian pharmacokinetic/pharmacodynamic forecasting of prothrombin response to warfarin therapy: preliminary evaluation. Therapeutic Drug Monitoring, 7, 174–180. Taylor, F., Ramsey, M., Voke, J. & Cohen, H. (1993) GPs not prepared for monitoring anticoagulation. British Medical Journal, 307, 1493. Vadher, B., Patterson, D.L.H. & Leaning, M. (1997) Evaluation of a decision support system for initiation and control of oral anticoagulation in a randomized trial. British Medical Journal, 314, 1252–1256. Wilson, R. & James, A.H. (1984) Computer assisted management of warfarin treatment. British Medical Journal, 289, 422–424. Wyld, P.J., West, D. & Wilson, T.H. (1988) Computer dosing in anticoagulant clinics – the way forward? Clinical and Laboratory Haematology, 10, 235–236.
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