Aim: To assess changing trends of abdominal aortic aneurysms 1979 - 1991. Design: Retrospective study from the Leicestershire Health Authority. Results.
Eur J VascEndovascSurg (1995) 9, 239-243
Trends in Abdominal Aortic Aneurysms: a 13 year review A. Nasim, R. D. Sayers, M. M. Thompson,
P.A. Healey and P. R. F. Bell
Department of Surgery, Clinical Sciences Building, Leicester Royal Infirmary, P O Box 65, Leicester, LE2 7LX, U.K. Aim: To assess changing trends of abdominal aortic aneurysms 1979 - 1991. Design: Retrospective study from the Leicestershire Health Authority. Results. 727 patients with abdominal aortic aneurysm were treated. Of these 56.4% were admitted for elective repair and 43.6% presented with rupture. There was a significant increase in the number of ruptured aortic aneurysms over this period despite an increase in the number of elective repairs. The overall 30-day mortality of elective repair (including patients with symptomatic but non-ruptured aneurysms) was 8.8%. The overall 30-day mortality of ruptured aneurysms (including patients who were deemed medically too unfit for surgery) was 57.7%. There has been no significant change in elective and ruptured mortality over the study period. There was a significant increase in the median age of patients (69.5 yrs in 1979 to 74 yrs in 1991). Conclusion: The increasing incidence of abdominal aortic aneurysms may reflect better diagnostic methods, greater clinical awareness of the condition and increase in the proportion of elderly people in the population. Key Words: Abdominal aortic aneurysm; Mortality; Elective repair; Rupture; Hospital admissions.
Introduction
Patients and Methods
Elective abdominal aortic aneurysm (AAA) repair is associated with a mortality of around 5% or less in most centres. ~'2 However the mortality of patients undergoing surgery for ruptured AAA remains greater than 50%.3-5 Ruptured AAAs are responsible for 1.3%6 of all deaths in men over the age of 65 years, accounting for around 10,000 deaths per annum in England and Wales. 7 Over the last 30 years there has been a progressive increase in the number of recorded deaths from AAA in England and Waless despite an increase in the number of elective AAA repairs. Several factors may account for this increase including the age of the population at risk, the ratio of males to females, the presence of known cardiovascular risk factors, greater awareness by general practitioners and greater use of ultrasound scanning for investigation of abdominal complaints. The aim of this study was to assess the changing trends of abdominal aortic aneurysms in Leicester between 1979 and 1991.
There are three hospitals in the Leicestershire Health Authority that provide vascular services: Leicester Royal Infirmary (LRI), Leicester General Hospital (LGH) and Glenfield General Hospital (GGH). Throughout the period of the study vascular surgery was undertaken at LRI and LGH. At GGH vascular surgery was only available from 1982 onwards. During the period of the study the population of Leicestershire increased from 836300 in 1979 to 890 800 in 1991. Data for this study was obtained from the Hospital Activities Analysis (HAA) database of the Leicestershire Health Authority from 1979 to 1987 and the Trent Regional Information System from 1987 to 1991. Data was complete for each year except between September 1986 and April 1987 for which no data was available. The two databases contain information on all patients discharged from hospitals serving the Leicestershire Health Authority, and each patient is coded according to diagnosis and treatment. The diagnosis codes are based on the International Classification of Diseases, ninth revision, clinical modification (ICD-9-CM) and the treatment codes are based on the Office of Populations, Censuses and Surveys (OPCS) classification of surgical operations, second,
Please address all correspondence to: A. Nasim, Department of Surgery, Clinical Sciences Building, LeicesterRoyal Infirmary,PO Box 65, Leicester,LE2 7LX,U.K.
1078-5884/95/020239 +05 $08.00/0 © 1995W. B. Saunders CompanyLtd.
A. Nasim et aL
240
third a n d fourth revisions. These databases p r o v i d e information on the patient's name, age, sex, presentation (elective or emergency), length of hospital sta)5 discharge a n d mortality. Using the t w o databases information w a s obtained on all patients a d m i t t e d for A A A surgery b e t w e e n 1979 a n d 1991. Patients were only included in the s t u d y if they h a d b o t h a diagnosis a n d treatment code. In addition, only patients a d m i t t e d to the 3 hospitals (LRI, L G H and G G H ) u n d e r general a n d vascular surgeons were included. Patients with thoracic and t h o r a c o - a b d o m i n a l aortic a n e u r y s m s admitted to the regional cardiothoracic unit (Groby Road Hospital), which is situated on a separate site, w e r e excluded. i
Statistical analysis For the years 1986 a n d 1987, data were complete for 8 m o n t h s of the year rather than the full year. It w a s a s s u m e d that there w a s no seasonal variation in a b d o m i n a l aortic a n e u r y s m surgery, a n d the figures for these years were multiplied b y 1.5 to p r o d u c e estimated rates for the full calendar year. The rates for each year were calculated b y using the m i d - y e a r estimated resident p o p u l a t i o n for Leicestershire, for the relevant year, as the denominator. Differences in the rates of variables with time were analysed b y regression with year as the i n d e p e n d e n t variable a n d rate as the d e p e n d e n t variable.
Table 1. Total number of elective and ruptured AAAs admitted for each year. Values in parentheses are rates per 100000 population
Year
Total*
Elective**
Ruptured***
1979
22 (2.6)
14 (1.7)
8 (0.9)
1980
30 (3.6)
18 (2.1)
12 (1.4)
1981
26 (3.0)
22 (2.6)
4 (0.5)
1982
46 (5.3)
26 (3.0)
20 (2.3)
1983
43 (4.9)
24 (2.8)
19 (2.2)
1984
51 (5.9)
30 (3.5)
21 (2.4)
1985
66 (7.6)
40 (4.6)
26 (2.9)
1986
65 (7.5)
43 (3.3)
22 (1.7)
1987
106 (11.9)
68 (5.1)
38 (2.8)
1988
83 (9.4)
39 (4.9)
44 (4.9)
1989
54 (6.1)
20 (2.2)
34 (3.8)
1990
58 (6.5)
24 (2.7)
34 (3.8)
1991
77 (8.6)
42 (4.7)
35 (3.9)
*ra = 0.54, p = 0.004 **r2 = 0.30, p = 0.05 ***r2 = 0.73, p = 0.0002 dramatically with age for b o t h elective a n d r u p t u r e d AAAs (Table 2). The overall m e d i a n age w a s 71 years (range 31-97 years). The m e d i a n age for elective A A A repair w a s 70 years (range 31-89), a n d 74 years for r u p t u r e d AAAs 12
Results 10
O v e r the 13-year period 1979-1991, a total of 727 patients w e r e a d m i t t e d to the three hospitals with AAA. Of these 410 (56.4%) patients were a d m i t t e d for elective repair a n d 317 (43.6%) presented with rupture. Table 1 s h o w s the n u m b e r of A A A s a d m i t t e d for each year. There has b e e n a significant increase (Fig. 1) in b o t h elective a n d r u p t u r e d a b d o m i n a l aortic aneur y s m s (p = 0.05 a n d p = 0.0002, respectively).
~ " o ~ o oo oo " m
O
•
Ruptured
Age and sex
@ .
79
The overall sex distribution w a s 5.5:1 male to female. The ratio for elective a n d r u p t u r e d AAAs w a s 7.5:1 a n d 4:1 respectively. There w a s a significant difference b e t w e e n m e d i a n age of presentation in m e n (70 yrs) a n d w o m e n (77 yrs). Also sex distribution changed Eur J Vasc Endovasc Surg Vol 9, February 1995
.
.
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i
81
.
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.
.
i
83
.
.
.
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!
85
.
.
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87
.
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89
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91
Year
Fig. 1. Rate of AAAs admitted per 100000 population of Leicestershire over the study period. Points axe fitted with best fit regression line.
Trends in Abdominal Aortic Aneurysms
Table 2. Male to female ratio for elective and ruptured A A A s according to age
Age group
Elective M:F ratio
Ruptured M:F ratio
Overall M:F ratio
< 64
15.7:1
46:0
23.3:1
65-74
8.9:1
4.8:1
6.86:1
75-84
4.1:1
3:1
3.44:1
2:1
1:1
1.13:1
> 85
Table 3. The median age of patients admitted w i t h A A A f r o m 1979-1991
Year
Median age of all AAAs (years)*
Median age of elective AAAs (years)**
Median age of ruptured AAAs (years)***
1979
69.5
69.5
70.5
1980
70.5
67.5
73.5
1981
70
70
59
1982
72.5
71
73.5
1983
68
65.5
72
1984
70
68.5
73
1985
70
70
71
1986
70
68
75
1987
71
70
72
1988
73
70
74
1989
74.5
69
78
1990
74
74.5
74
1991
74
71.5
76
*ra = 0.53, p = 0.005 **r2 = 0.23, p = 0.09 ***r2 = 0.30, p = 0.05 (range 48-97 years). Table 3 s h o w s the c h a n g e in the m e d i a n age of patients a d m i t t e d w i t h A A A o v e r the s t u d y period. Overall there w a s a significant increase in the m e d i a n age of patients o v e r the s t u d y p e r i o d (r 2 = 0.53, p = 0.005). There w a s n o significant increase in the m e d i a n ages,0f elective (p = 0.09) a n d r u p t u r e d A A A s (p = 0.05 i o v e r the s t u d y period.
241
Table 4. Percentage hospital mortality of elective and ruptured AAAs for each year. Values in parentheses are the number of deaths
Year
% mortality of elective AAA repair*
% mortality of ruptured AAAs**
1979
14.3 (2)
62.5 (5)
1980
22.2 (4)
91.7 (11)
1981
9.1 (2)
25 (1)
1982
15.4 (4)
65 (13)
1983
4.2 (1)
68.4 (13)
1984
6.7 (2)
66.7 (14)
1985
7.5 (3)
5z7 (15)
1986
7.0 (3)
63.6 (14)
1987
5.9 (4)
34.2 (13)
1988
10.3 (4)
63.6 (28)
1989
10.0 (2)
61.8 (21)
1990
4.2 (1)
47.1 (16)
1991
9.5 (4)
54.3 (19)
*r2 = 0.29, p = 0.06 **r2 = 0.068, p = 0.4
r u p t u r e d A A A s for each year. F o u r - h u n d r e d - a n d - t e n patients (56.4%) u n d e r w e n t elective repair w i t h an overall 3 0 - d a y m o r t a l i t y of 8.8% (including patients with symptomatic but non-ruptured aneurysms who r e q u i r e d u r g e n t surgery). There w a s n o significant c h a n g e (p = 0.06) in the m o r t a l i t y of elective repair d u r i n g the s t u d y p e r i o d (Fig. 2). T h r e e - h u n d r e d - a n d s e v e n t e e n patients (43.6%) w e r e a d m i t t e d w i t h r u p t u r e d A A A w i t h a n overall 3 0 - d a y m o r t a l i t y of 57.7% (including patients w h o w e r e d e e m e d m e d i c a l l y too unfit for surgery). There has b e e n n o significant c h a n g e (p = 0.4) in the m o r t a l i t y of r u p t u r e d A A A s (Fig. 2) d u r i n g the s t u d y period. M o r t a l i t y of patients u n d e r g o i n g elective A A A repair a n d those p r e s e n t i n g w i t h r u p t u r e w a s anal y s e d a c c o r d i n g to age a n d sex (Table 5). There w a s a n increase in the p e r c e n t a g e m o r t a l i t y of elective a n d r u p t u r e d A A A s w i t h increasing age in b o t h m a l e s a n d females.
Hospital stay Mortality Table 4 s h o w s the h o s p i t a l m o r t a l i t y of elective a n d
For those patients s u r v i v i n g elective a n e u r y s m repair the m e d i a n hospital stay w a s 14 d a y s (range 6-85 Eur J Vasc Endovasc Surg Vol 9, February 1995
242
A. Nasim et aL
days). The median hospital stay for those patients surviving emergency repair was 17 days (range 8--60 days).
Table 5. Percentage mortality for elective and ruptured AAAs according to sex and age group. Values in parentheses are the number of deaths Sex
Age range
% Elective mortality
% Ruptured mortality
Males
< 64 65-74 7544 > 85
5.3 6.2 21.6 50.0
45.6 44.8 73.9 86.7
Females
< 64 65-74 75-84 > 85
0 0
Discussion
This study shows that there has been an increase in the workload of AAAs over the last 13 years in our centre. This may partly be due to better diagnostic methods, greater clinical awareness and increase in the number of elderly people in the catchment population. This is reflected by the increase in the median age of the patients (69.5 yrs in 1979 to 74 yrs in 1991) in our study. However the trends observed in our study and those of others 4'7'9 suggest that there is probably a true increase in the incidence of aortic aneurysms. Establishment of community screening programmes for aortic aneurysms may in the long term provide a true picture of the changing prevalence of this condition. The overall 30-day mortality for elective repair was 8.8%. However this figure includes patients with symptomatic ('acute') aneurysms which have a mortality of 10-15% in most centres. 3 The overall 30-day mortality for ruptured AAAs was 57.7%. This figure includes patients who were deemed medically too unfit to undergo surger)~ those dying in casualty and those that died on the operating table. Also in the early years of the study period, AAAs in our centre were also operated on by general surgeons and higher surgical trainees (registrars and senior registrars) until 100 []
Elective
•
Ruptured
80
~
60
0
E 0 0~
40
0
.u 0 a.
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20
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(5) (10) (16) (1)
22.2 (4) 0
(21) (39) (65) (13)
0 50.0 (9) 86.2 (25) 78.6 (11)
the introduction of a vascular rota. However there is no data to see if there has been any change in mortality. There was no significant change in the mortality of ruptured AAAs over the study period. The high mortality may partly be due to more elderly patients ( > 80 yrs) presenting to the hospital with rupture and this is reflected by an increase in the median age of patients (70.5 yrs in 1979 to 76 yrs in 1991). The outcome of surgery in these patients is difficult to predict preoperatively,5 because it is difficult to assess patients fully when they present with rupture. Also despite successful surgery many develop cardiac failure, renal failure and coagulopathy postoperatively. Therefore as surgical reconstruction offers the only chance of survival, surgery should invariably be offered. However the poor outcome of surgery with increasing age is reflected in our study (around 80% mortality in > 85 yrs age group compared with < 45% mortality in the 65-74 age group). It is clear from this study and other reported series that hospital mortality of ruptured AAAs remains high and there has been little improvement over the last decade despite advances in surgery and anaesthesia. There are two possible strategies which may have a big impact in the future. Firstly establishment of ultrasound screening programmes may detect aneurysms before they present with rupture, enabling elective repair, m'n Also previously some patients have been denied elective repair because of old age and concurrent medical disease increasing risks of surgery. The endovascular treatment of AAAs is an exciting prospect for this group of patients. The early clinical results 12q4 are encouraging and this technique promises much for the future.
91
Year References Fig. 2. Comparison of hospital mortality of elective (r2 = 0.29, p = 0.06) a n d r u p t u r e d (r2 = 0.068, p = 0.4) AAAs in Leicester from 1979-1991. Points are fitted with best fit linear regression line.
Eur J Vasc Endovasc Surg Vol 9, February 1995
1 MAKIN GS. Changing fashions in the surgery of aortic aneurysms. Ann R Coll Surg Engl 1983; 65: 308-310.
Trends in Abdominal Aortic Aneurysms
2 FIELDING JWL, BLACK J/ ASHTON F, SLANEY J/ CAMPBELL DJ. Diagnosis and management of 528 abdominal aortic aneurysms. BMJ 1981; 283: 355-359. 3 CAMPBELLWB, COLLINJ, MORRISPJ. The mortality of abdominal aortic aneurysm. Ann R Coll Surg Engl 1986; 68: 275-278. 4 SAMY AK AND MAcBAIN G. Abdominal aortic aneurysm: Ten years' hospital population study in the city of Glasgow. Eur J Vasc Surg 1993; 7: 561-566. 5 HARRIS LM, FAGGIOLI GL, FIEDER R, CURL GR, RrCOTTA JJ. Ruptured abdominal aortic aneurysms: Factors affecting mortality rates. J Vasc Surg 1991; 14: 812-820. 6 Mortality statistics cause: review of the Registrar General on deaths by cause, sex and age in England and Wales 1983. Series DH2 No. 10, Her Majesty's Stationery Office. 7 FOWKES FGR, MAC~NTYRECCA, RUCKLEYCV. Increasing incidence of aortic aneurysms in England and Wales. BMJ 1989; 298: 33-35. 8 COLLINJ. The epidemiology of abdominal aortic aneurysm. Br J Hosp Med 1988; 40: 64-67.
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9 BUDD JS, FINCH DRA, CARTERPC. A study of mortality from ruptured Abdominal aortic aneurysms in a District Community. Eur J Vasc Surg 1989; 3: 351-354. 10 COLLINJ. Screening for abdominal aortic aneurysm. Br ] Surg 1993; 80: 1363-1364. 11 HARRIS PL. Reducing the mortality from abdominal aortic aneurysms: need for a national screening programme. BMJ 1992; 305: 697-699. 12 PARODIJC. Endovascular repair of Abdominal aortic aneurysms. In: Advances in Vascular Surgery, Vol. 1. Mosby-Year Book Inc. 1993: pp 85-106. 13 SCOTTRAP, CHUTERTAM, Clinical endovascular placement of bifurcated graft in abdominal aortic aneurysm without laparotomy (communication). Lancet 1994; i: 413. 14 NASIM A, SAYERS RD, THOMPSON MM, BELL PRF, BOLIA A. Endovascular repair of aortic aneurysms (communication). Lancet 1994; i: 1230-1231.
Accepted 11 October 1994
Eur J Vasc Endovasc Surg Vol 9, February 1995
