Dm
CLINICAL PRACTICE
A Survey of lower Limb Amputation in Diabetic Patients C. Deerochanawong, P.D. Home, K.C.M.M. Alberti Department of Medicine, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne, UK
A retrospective survey of non-traumatic and non-neoplastic lower limb amputations in Newcastle upon Tyne during 1989-91 was performed. Hospital data were cross-checked with the local limb fitting centre to ensure 100 % ascertainment. The diabetic patients were found to be 39 % of amputees and 42 % of operations (all levels). Incidence of diabetes amputation was 5.7 per 100000 population per year. Fifteen percent of the diabetic patients had diabetes first diagnosed when they were admitted for amputation. For the known diabetes patients, 46 % were under diabetes care by general practitioners only. Forty-seven percent of the patients who were under the care of a hospital service for diabetes had incomplete foot examination and assessment. Mortality rate within 30 days after diabetic amputation was 10 % and median life expectancy following amputation was 22 months. It seems likely that assessment and management of the diabetic foot remains suboptimal in Newcastle, and that protocols and audit of care could lead to improvements without additional resources. KEY WORDS
Diabetes mellitus Amputation
Introduction Lower limb amputation is a major health problem in the diabetic population and is associated with significant morbidity, mortality, and disability.' Diabetic patients are predisposed to lower limb amputation primarily through the development of peripheral neuropathy and peripheral vascular disease. In one study, individuals with diabetes experienced an age adjusted rate of lower limb amputation 15 times that of people without diabetes.2 The application of patient education and training in foot care can lead to a dramatic reduction in amputation rate^.^ We therefore reviewed the clinical characteristics and outcomes in all diabetic patients who underwent lower limb amputation between 1989 and 1991 in the hospitals in Newcastle upon Tyne (UK) to determine trends and patterns of diabetes-related lower limb amputation and to identify the group at high risk of having lower limb amputation toward whom intervention activities could be targeted.
Patients and Methods All the patients who underwent lower limb amputations between 1 January 1989 and 31 December 1991 in the Newcastle upon Tyne hospitals were identified by using the Department of Surgery operation records plus hospital coding of discharge details for lower limb amputation by using Office of Population Consensus and Surveys, 4th revision, code X09-X11 . 4 The three National Health Correspondence to: Dr P. D. Home, Department of Medicine, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
942
0742-3071/92/100942-05$07.50
0 1992 by John Wiley & Sons,
Ltd.
Epidemiology
Service hospitals treat al I patients referred for secondary care within the Newcastle Health District, with the exception of those referred to a small private hospital. As a check on completeness of ascertainment of patients having amputation, lists of patients receiving care at the only limb fitting centre in Newcastle upon Tyne were examined. Medical records of all amputees were reviewed. Diagnosis of diabetes was ascertained from these medical records because of the likelihood of under-reporting of diabetes on hospital discharge forms. Traumatic and neoplastic lower limb amputations were excluded. All the diabetic patients having lower limb amputation during the period of study who lived in Newcastle upon Tyne Health District were ascertained. Data were extracted on age, sex, duration of diabetes, diabetes treatment, site care of diabetes, extent of amputation, history of previous amputation, smoking habit, history of intermittent claudication, history of foot ulcer, and previous year records of foot examination before detection of ulcer or gangrene. Information was similarly obtained on the presence or absence of dorsalis pedis/posterior tibia1 pulses, presence or absence of ankle jerk, pinprick and vibration sensation of lower limbs, and details of angiograms, angioplasty, and vascular bypass surgery of the limb before amputation. The site of diabetes care was classified as general practitioner (GP) only, hospital only, and shared care. Hospital care was considered if the patients visited the hospital regularly (three or more visits a year), and shared care was considered if the patients were under care for diabetes by their GP and visited the diabetic clinic once or twice per year. Peripheral vascular disease was diagnosed if there was record of a history of intermittent Accepted 10 July 1992 DIABETIC MEDICINE, 1992; 9: 942-946
DTT7 claudication or absence of dorsalis pedis/posterior tibia1 pulse. Peripheral neuropathy was diagnosed if there was absence of ankle jerk or loss of pinprick or vibration sensation of lower limbs. The clinical course of patients as regards further amputation and survival was followed until the end of January 1992, giving a range of follow-up of 1 to 36 months.
Statistical Analysis Statistical tests including Mann-Whitney U-test, Chi square test, or Fisher’s exact test were used as appropriate. A p-value less than 0.05 was taken as significant.
Results Amputation Incidence From 1 January 1989 to 31 December 1991, 120 nontraumatic lower limb amputations were performed in 93 diabetic patients and 165 non-traumatic lower limb amputations on 143 non-diabetic people in Newcastle upon Tyne. The diabetic patients thus formed 39 % of patients and 42 % of operations. Among the 93 people with diabetes, 48 patients lived in Newcastle upon Tyne and 45 patients were referred from outside the city. By the Office of Population Census and Surveys, 279260 inhabitants were in Newcastle upon Tyne in mid-year 1990. Thus the incidence of non-traumatic lower limb amputation in diabetes was 5.7 per 100000 inhabitants per year. If the prevalence of diagnosed diabetes in Newcastle is 1.O Yo as in the Oxford, Poole and Southall study,5 the incidence of non-traumatic lower limb amputation was 5.7 per 1000 diabetic patients per year. Of the diabetic amputees living in Newcastle, 36 (75 %) were male and 12 (25 %) were female, virtually identical to the non-diabetic sex distribution. Age at amputation was 71 (mean, range 54-85) years for male and 67 (range 27-88) years for female patients. Thirtyone (65 %) were aged over 65 years. Duration of diabetes was 7 (0-27) years. In 7 patients (15 %) diabetes was first diagnosed when they were admitted for the amputation.
Treatment and Site of Diabetes Care Of the 41 patients who were known to have diabetes before admission for the operation, 3 (7 Yo)were managed by diet alone, 25 (61 %) with oral hypoglycaemic agents, and 13 (32 YO)were on insulin therapy. Nineteen (46 %) were managed by their general practitioner only, 17 (42 YO)were under hospital care and 5 (12 %) were in shared care. More of the patients who were attending hospital were treated with insulin than those under GP care alone (77 vs 8 %). LOWER LIMB AMPUTATION IN DIABETES
CLINICAL PRACTICE Predisposing Factor for Amputation Of the 48 diabetic amputees, 42 patients (88 %) had evidence of peripheral vascular disease. Twenty-five of the 39 patients (64 YO)in whom there was a record of neurological examination had evidence of peripheral neuropathy and 26 of the 48 patients (54 %) had a foot ulcer before amputation. Eleven of the 48 patients (23 %) had a previous history of lower limb amputation before the study period, 3 in the same leg and 8 in the contralateral leg. Eighteen of the 48 patients (38 %) were currently smoking.
Level of Amputation The most proximal lower limb amputation in 48 diabetic patients during the study period was as follows: 15 (31 %) had toe amputation, 3 (6 %) had forefoot amputation, 22 (46 Yo) had below knee amputation, and 8 (17 %) had above knee amputation. Table 1 compares the clinical characteristics and risk status of patients who had minor (toe and forefoot) or major (below and above knee) amputation. The only statistically significant difference between these groups was the almost universal presence of peripheral vascular disease in the major amputation group (Table 1).
Table 1 . Clinical characteristics and risk status of patients having minor and major amputation Level of amputation Minor (toe and forefoot)
Major (below and above knee)
18
30
n Age (yr)
68.7
?
11.8
71.7
* 13.5
15:3
21 :9
7 (0-27)
5 (0-25)
Treatment of diabetes (%) New case Diet only Oral hypoglycaemic drug Insulin
16.7 0 55.5 27.8
13.3 10.0 50.0 26.7
Site of diabetes care (%) New case G P care Hospital care Shared care
16.7 27.8 38.9 16.6
13.3 40.0 36.7 10.0
72.2
96.7’
58.8
68.2
Sex (M:F) Duration of diabetes (yr)
Presence of peripheral vascular disease (%) Presence of peripheral neuropathy (%)
Mean f SD, median (range), number, or percent. “ p = 0.020.
943
DT17
CLINICAL PRACTICE Preoperative Investigation and Vascular Surgery
Discussion
Of the 42 diabetic amputees who had evidence of peripheral vascular disease, 19 (45 %) had had an angiogram before amputation. Fourteen patients had undergone angioplasty, 1 patient vasuclar bypass surgery, and 1 patient both procedures.
'
Diabetes f o o t Care in the Year Before Detection of f o o t Ulcer or Gangrene It proved impossible to review earlier diabetes care of
patients under GP care alone, due to absence of records or loss of records or death or moving away in the majority. Considering only the diabetic amputees who were under hospital care for diabetes before amputation, only 11 of the 17 patients (65 %) had any record of foot shape or skin condition. Thirteen patients (77 %) had evidence of examination of peripheral pulses and 10 (59 %) had evidence of examination for peripheral neuropathy before the first detection of ulceration or gangrene. Complete foot evaluation was found in only 9 (53 %) of the 17 patients.
Amputation and Mortality The mortality rate within 30 days of amputation was 10 %, and the survival curve for life is shown in Figure 1. Median life expectancy following amputation was 22 months. During the 1-36 month follow-up, 9 of 48 (19 %) had a further amputation, 6 in the same leg and 3 in the contralateral leg.
1
0.8
.-> z
G
0.6
0.4
1
Om2 0 1 0
1
-
6
1
I
I
1
12
18
24
30
Months after amputation Figure 1. Life table analysis showing survival in months after amputation in 48 diabetic patients. The methodology used follows that in Kahn2'
944
There are marked differences in the incidence of lower limb amputation in diabetes populations as shown in Table 2. Many factors may contribute to this including prevalence of diabetes, resources available for diabetes care, prophylactic foot care, and vascular surgery. Our study and most of the other studies are retrospective except for the Pima Indians and Wisconsin studies.2+'o The Pima Indians have the world's highest reported prevalence of diabetes,' and this may explain why they had the highest incidence of diabetes amputation.8 Our study excluded traumatic and neoplastic causes of amputation in order to look for the amputation that related to diabetes, in contrast to the Danish and six states in USA A study in two separate parts of Sweden concluded that prophylactic foot care was the most important factor in explaining the large differences in rate of diabetes amputation in the same country,' but our data are comparable to the better Swedish region despite evidently inadequate medical management. The Danish study showed that there was an overall reduction in lower limb amputation for diabetes in Denmark from 1980 to 1989, and suggests that the time of study is also important.6 An additional variable in the calculations is the background prevalence of diabetes. If this is greater than the 1.0 % taken from elsewhere in the UK,5 then the incidence of amputation will be less than the calculated 5.7 1000-' yr-'. A further factor is the level of amputation, as 37 % of operations in our series were below ankle procedures. Our study found that 42 % of lower limb amputations were performed in diabetic patients. This is comparable with the data of previous ~tudies.~,~,' Most of the studies including our own show that incidence of diabetic lower limb amputation is higher in men (three times that in women), and that the elderly are particularly a f f e ~ t e d . ~ , ~ , ~ , 'One ~ - ' ' factor that may contribute to the male predominance is higher rates of smoking in men,15 but the precise reasons for the marked increase in amputation with age are unknown." Two studies show that there is association between amputation and longer duration of known diabetes,a,'o but no studies show data of the relationship between newly diagnosed diabetes and diabetic amputation. Our study found that, in 15 % of the amputees, the diabetes was newly diagnosed, a figure that is quite high and supports a need for increased awareness of, even screening for, diabetes in high-risk groups.18 It is also a reminder that duration from diagnosis may be very different from duration of the disease. About 38 % (16142) of diabetic amputees who had evidence of peripheral vascular disease had had angioplasty or vascular bypass surgery before amputation. This figure appears to be low, as arterial reconstruction is clearly more cost effective and successful than a m p ~ t a t i o n . 'Our ~ data showing that angioplasty was more frequent than vascular bypass surgery may be C. DEEROCHANAWONG ET AL.
DTT7
CLINICAL PRACTICE Table 2. Comparison incidence of lower limb amputation in diabetes Region and reference
Year
Incidence 1 00 000 population-' yr-'
Newcastle upon Tyne (UK) Denmark6 Denmark" Gotland (Sweden)' Umea (Sweden)' Pima Indians (USA)* Wisconsin study (USA)'O Six States (USA)*
1989-1 991 1989 1981 1971-1980 1971-1980 1972-1 984 198&1986 1976-1 978
Tayside ( S ~ o t l a n d ) ~
1980-1 982
5.7 7
Incidence 1000 diabetes-' yr-' 5.7" b
11
b
20.5 6.5 206
b
b
b b
b
13.7 5.5 5.9 10.1
"Assumes prevalence as in other parts of the UK. bData not available.
surprising, given that reconstructive surgery is usually the treatment of choice for patients with chronic limb ischaemia due to extensive obstructions.20,2' One of the recommendations of the European Consensus Group on chronic critical limb ischaemia is that no patient should undergo primary amputation without considering for reconstructive vascular surgery.lg It is unclear as to why it was felt that over half of the patients would not benefit from contrast investigation. Evidence of complete foot examination including general inspection, and assessment of peripheral nerve and vascular status before first detection of ulcer or gangrene was found in only 53 % of the diabetic amputees who were under the care of hospital diabetes clinics. This sad figure is similar to that found by other investigators.22Complete foot evaluation at least annually should lessen this problem, and certainly is a prerequisite for targeted education programmes. Two of the three hospitals in our study have the annual review clinic separate from the regular review clinic, but foot evaluation was still poor as many pre-amputees failed to attend for the annual review. There are several studies of clinical intervention that have demonstrated that proper foot care programmes may reduce the frequency of amputation among those with d i a b e t e ~ . ~ The , ~ ~ complete ,~~ programme should include identification, evaluation, and treatment of highrisk individuals, patient education, and professional education. Individuals at high risk for lower limb amputation must be identified, evaluated, and treated according to this risk status. Intervention should also cover the behaviour required for good health in the general population, including cessation of smoking, exercise, weight control, hypertension, and cholesterol control. A team approach to comprehensive foot care at the primary care level for individuals with diabetes should involve the nurse, the GP, the diabetes educator, and the c h i r ~ p o d i s t .Unfortunately ~~ our study has no data on chiropodial care and patient education. There are some data in a recent survey showing that provision of LOWER LIMB AMPUTATION IN DIABETES
chiropody services in the UK was suboptimal and hospital chiropodists have little contact with the GP.26Professional education should be aimed at all members of health care teams including those in primary health care. In our study 42 % of diabetic patients requiring lower limb amputation were under diabetes care by GPs alone, if under review at all. Thus, primary health care teams also need guidelines for identification of high-risk patients, performance of regular foot examination, and assessment of clinical risk, education, and treatment methods, and when to refer the patients for specialist care.
Acknowledgements
C. Deerochanawong was supported by a British Council fellowship. The authors are grateful to Mr J.Chamberlain, Mr N.A.G. Jones, Mr D. Lambert, Dr S.M. Marshall, Mr G. Proud, Dr R. Taylor and Dr W.M.G. Tunbridge for permitting us to look at the surgical operation records and medical records for patients under their care.
References 1. Mazze R, Sinnock P, Deeb L, Brimberry J. An epidemiological model for diabetes mellitus in the United States: five major complications. Diab Res Clin Prac 1985; 1: 185-191. 2. Most RS, Sinnock P. The epidemiology of lower extremity amputation in diabetic individuals. Diabetes Care 1983; 6:87-91. 3. Assal JP, Muhlhauser I, Pernet A, Gfeller R, Jorgens V, Berger M. Patient education as the basis for diabetes care in clinical practice. Diabetologia 1985; 28: 602-61 3. 4. Office of population consensus and surveys. Classification of surgical operations and procedures. Fourth revision, London: HMSO, 1990. 5. Neil HAW, Gatling W, Mather HM, Thompson AV, Thorogood M, Fowler GH, et a/. The Oxford Community diabetes study evidence for an increase in the prevalence of known diabetes in Great Britain. Diabetic Med 1987; 4: 539-543.
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CLINICAL PRACTICE 6. 7. 8.
9. 10. 11.
12. 13. 14. 15. 16.
946
Ebskov LB. Epidemiology of lower limb amputations in diabetics in Denmark. Int Orthop 1991; 15: 285-288. Lindegard P, Jonsson6, Lithner F. Amputations in diabetic patients in Gotland and Umea countries 1971-1 980. Acta Med Scand 1984; 687 suppl: 89-93. Nelson RG, Gohdes DM, Everhart JE, Hartner )A, Zwemer FL, Pettitt DJ, et a/. Lower extremity amputations in NIDDM: 12 year follow-up study in Pima Indians. Diabetes Care 1988; 11: 8-16. Waugh NR. Amputations in diabetic patients: a review of rates, relative risks and resource use. Community Med 1988; 10: 279-288. Moss S, Klein R, Klein B. The prevalence and incidence of lower extremity amputation in a diabetic population. Arch Intern Med 1992; 152: 610-616. Knowler WC, Bennett Ph, Hamman RF, Miller M. Diabetes incidence and prevalence in Pima Indians: a 1%fold greater incidence than Rochester, Minnesota. Am I Epidemiol 1978; 108: 497-505. Kald A, Carlsson R, Nilsson E. Major amputation in a defined population: incidence, mortality and results of treatment. Br I Surg 1989; 76: 308-310. Miller AD, Van Buskirk A, Verhock-Oftedahl W, Miller ER. Diabetes related lower extemity amputations in New Jersey, 1979-1081. Med SOC N] 1985; 82: 712-726. De Stefan0 F, Dougherty BL, Ford ES. Diabetes surveillance, 1980-1 987. Atlanta GA: Centres for Disease Control; 1990: 23-25. West KM. Epidemiology of Diabetes and its Vascular Lesions. New York: Elsevier, 1978: 84-1 26. Rose C, Mclntosh C. Amputation: is diabetes an underdiagnosed cause? Practical Diabetes 1991; 8: 146-1 47.
17.
Falkel J. Amputation as a consequence of diabetes mellitus: An epidemiological review. Physical Therapy 1983; 63: 960-964. 18. Position statement by American Diabetes Association. Screeningfor diabetes. Diabetes Care 1989; 12: 588-590. 19. European Working Group on Critical Limb Ischaemia. Second European Consensus document on chronic critical limb ischaemia. Circulation 1991; 84 (suppl 4): 1-26. 20. Bell PFR. Indications for aortoiliac and aortofemoral bypass grafts for lower limb ischaemia. In: Greenhalgh RM, eds. Indications in Vascular Surgery. Philadelphia: WB Saunders, 1988: 189-21 3. 21. Adar R, Critchfield GC, Eddy DM. A confidence profile analysis of the results of femoro-popliteal percutaneous transluminal angioplasty in the treatment of lower leg ischaemia. 1 Vas Surg 1989; 10: 29-38. 22. Bailey T, Yu H, Rayfield E. Patterns of foot examination in a diabetes clinic. Am Med 1985; 78: 371-374. 23. Edrnonds ME. Blundell MP, Morris HE, Thomas EM, Cotton LT, Watkins PJ. The diabetic foot: impact of a foot clinic. QI Med 1986; 232: 763-761. 24. Runyan JW. The Memphis chronic disease program. IAMA 1975; 231: 264-267. 25. Boulton AJM. The diabetic foot. Med Clin North Am 1988; 72: 1513-1530. 26. British Diabetes Association. Diabetes and Chiropodial Care. Report on the findings by a Joint Working Party of the British Diabetic Association and the Society of Chiropodists. London: BDA, 1990. 27. Kahn HA. Statistical Methods in Epidemiology. New York: Oxford University Press, 1989: 169-205.
C. DEEROCHANAWONC ET AL.
CLINICAL PRACTICE
A Survey of lower Limb Amputation in Diabetic Patients C. Deerochanawong, P.D. Home, K.C.M.M. Alberti Department of Medicine, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne, UK
A retrospective survey of non-traumatic and non-neoplastic lower limb amputations in Newcastle upon Tyne during 1989-91 was performed. Hospital data were cross-checked with the local limb fitting centre to ensure 100 % ascertainment. The diabetic patients were found to be 39 % of amputees and 42 % of operations (all levels). Incidence of diabetes amputation was 5.7 per 100000 population per year. Fifteen percent of the diabetic patients had diabetes first diagnosed when they were admitted for amputation. For the known diabetes patients, 46 % were under diabetes care by general practitioners only. Forty-seven percent of the patients who were under the care of a hospital service for diabetes had incomplete foot examination and assessment. Mortality rate within 30 days after diabetic amputation was 10 % and median life expectancy following amputation was 22 months. It seems likely that assessment and management of the diabetic foot remains suboptimal in Newcastle, and that protocols and audit of care could lead to improvements without additional resources. KEY WORDS
Diabetes mellitus Amputation
Introduction Lower limb amputation is a major health problem in the diabetic population and is associated with significant morbidity, mortality, and disability.' Diabetic patients are predisposed to lower limb amputation primarily through the development of peripheral neuropathy and peripheral vascular disease. In one study, individuals with diabetes experienced an age adjusted rate of lower limb amputation 15 times that of people without diabetes.2 The application of patient education and training in foot care can lead to a dramatic reduction in amputation rate^.^ We therefore reviewed the clinical characteristics and outcomes in all diabetic patients who underwent lower limb amputation between 1989 and 1991 in the hospitals in Newcastle upon Tyne (UK) to determine trends and patterns of diabetes-related lower limb amputation and to identify the group at high risk of having lower limb amputation toward whom intervention activities could be targeted.
Patients and Methods All the patients who underwent lower limb amputations between 1 January 1989 and 31 December 1991 in the Newcastle upon Tyne hospitals were identified by using the Department of Surgery operation records plus hospital coding of discharge details for lower limb amputation by using Office of Population Consensus and Surveys, 4th revision, code X09-X11 . 4 The three National Health Correspondence to: Dr P. D. Home, Department of Medicine, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
942
0742-3071/92/100942-05$07.50
0 1992 by John Wiley & Sons,
Ltd.
Epidemiology
Service hospitals treat al I patients referred for secondary care within the Newcastle Health District, with the exception of those referred to a small private hospital. As a check on completeness of ascertainment of patients having amputation, lists of patients receiving care at the only limb fitting centre in Newcastle upon Tyne were examined. Medical records of all amputees were reviewed. Diagnosis of diabetes was ascertained from these medical records because of the likelihood of under-reporting of diabetes on hospital discharge forms. Traumatic and neoplastic lower limb amputations were excluded. All the diabetic patients having lower limb amputation during the period of study who lived in Newcastle upon Tyne Health District were ascertained. Data were extracted on age, sex, duration of diabetes, diabetes treatment, site care of diabetes, extent of amputation, history of previous amputation, smoking habit, history of intermittent claudication, history of foot ulcer, and previous year records of foot examination before detection of ulcer or gangrene. Information was similarly obtained on the presence or absence of dorsalis pedis/posterior tibia1 pulses, presence or absence of ankle jerk, pinprick and vibration sensation of lower limbs, and details of angiograms, angioplasty, and vascular bypass surgery of the limb before amputation. The site of diabetes care was classified as general practitioner (GP) only, hospital only, and shared care. Hospital care was considered if the patients visited the hospital regularly (three or more visits a year), and shared care was considered if the patients were under care for diabetes by their GP and visited the diabetic clinic once or twice per year. Peripheral vascular disease was diagnosed if there was record of a history of intermittent Accepted 10 July 1992 DIABETIC MEDICINE, 1992; 9: 942-946
DTT7 claudication or absence of dorsalis pedis/posterior tibia1 pulse. Peripheral neuropathy was diagnosed if there was absence of ankle jerk or loss of pinprick or vibration sensation of lower limbs. The clinical course of patients as regards further amputation and survival was followed until the end of January 1992, giving a range of follow-up of 1 to 36 months.
Statistical Analysis Statistical tests including Mann-Whitney U-test, Chi square test, or Fisher’s exact test were used as appropriate. A p-value less than 0.05 was taken as significant.
Results Amputation Incidence From 1 January 1989 to 31 December 1991, 120 nontraumatic lower limb amputations were performed in 93 diabetic patients and 165 non-traumatic lower limb amputations on 143 non-diabetic people in Newcastle upon Tyne. The diabetic patients thus formed 39 % of patients and 42 % of operations. Among the 93 people with diabetes, 48 patients lived in Newcastle upon Tyne and 45 patients were referred from outside the city. By the Office of Population Census and Surveys, 279260 inhabitants were in Newcastle upon Tyne in mid-year 1990. Thus the incidence of non-traumatic lower limb amputation in diabetes was 5.7 per 100000 inhabitants per year. If the prevalence of diagnosed diabetes in Newcastle is 1.O Yo as in the Oxford, Poole and Southall study,5 the incidence of non-traumatic lower limb amputation was 5.7 per 1000 diabetic patients per year. Of the diabetic amputees living in Newcastle, 36 (75 %) were male and 12 (25 %) were female, virtually identical to the non-diabetic sex distribution. Age at amputation was 71 (mean, range 54-85) years for male and 67 (range 27-88) years for female patients. Thirtyone (65 %) were aged over 65 years. Duration of diabetes was 7 (0-27) years. In 7 patients (15 %) diabetes was first diagnosed when they were admitted for the amputation.
Treatment and Site of Diabetes Care Of the 41 patients who were known to have diabetes before admission for the operation, 3 (7 Yo)were managed by diet alone, 25 (61 %) with oral hypoglycaemic agents, and 13 (32 YO)were on insulin therapy. Nineteen (46 %) were managed by their general practitioner only, 17 (42 YO)were under hospital care and 5 (12 %) were in shared care. More of the patients who were attending hospital were treated with insulin than those under GP care alone (77 vs 8 %). LOWER LIMB AMPUTATION IN DIABETES
CLINICAL PRACTICE Predisposing Factor for Amputation Of the 48 diabetic amputees, 42 patients (88 %) had evidence of peripheral vascular disease. Twenty-five of the 39 patients (64 YO)in whom there was a record of neurological examination had evidence of peripheral neuropathy and 26 of the 48 patients (54 %) had a foot ulcer before amputation. Eleven of the 48 patients (23 %) had a previous history of lower limb amputation before the study period, 3 in the same leg and 8 in the contralateral leg. Eighteen of the 48 patients (38 %) were currently smoking.
Level of Amputation The most proximal lower limb amputation in 48 diabetic patients during the study period was as follows: 15 (31 %) had toe amputation, 3 (6 %) had forefoot amputation, 22 (46 Yo) had below knee amputation, and 8 (17 %) had above knee amputation. Table 1 compares the clinical characteristics and risk status of patients who had minor (toe and forefoot) or major (below and above knee) amputation. The only statistically significant difference between these groups was the almost universal presence of peripheral vascular disease in the major amputation group (Table 1).
Table 1 . Clinical characteristics and risk status of patients having minor and major amputation Level of amputation Minor (toe and forefoot)
Major (below and above knee)
18
30
n Age (yr)
68.7
?
11.8
71.7
* 13.5
15:3
21 :9
7 (0-27)
5 (0-25)
Treatment of diabetes (%) New case Diet only Oral hypoglycaemic drug Insulin
16.7 0 55.5 27.8
13.3 10.0 50.0 26.7
Site of diabetes care (%) New case G P care Hospital care Shared care
16.7 27.8 38.9 16.6
13.3 40.0 36.7 10.0
72.2
96.7’
58.8
68.2
Sex (M:F) Duration of diabetes (yr)
Presence of peripheral vascular disease (%) Presence of peripheral neuropathy (%)
Mean f SD, median (range), number, or percent. “ p = 0.020.
943
DT17
CLINICAL PRACTICE Preoperative Investigation and Vascular Surgery
Discussion
Of the 42 diabetic amputees who had evidence of peripheral vascular disease, 19 (45 %) had had an angiogram before amputation. Fourteen patients had undergone angioplasty, 1 patient vasuclar bypass surgery, and 1 patient both procedures.
'
Diabetes f o o t Care in the Year Before Detection of f o o t Ulcer or Gangrene It proved impossible to review earlier diabetes care of
patients under GP care alone, due to absence of records or loss of records or death or moving away in the majority. Considering only the diabetic amputees who were under hospital care for diabetes before amputation, only 11 of the 17 patients (65 %) had any record of foot shape or skin condition. Thirteen patients (77 %) had evidence of examination of peripheral pulses and 10 (59 %) had evidence of examination for peripheral neuropathy before the first detection of ulceration or gangrene. Complete foot evaluation was found in only 9 (53 %) of the 17 patients.
Amputation and Mortality The mortality rate within 30 days of amputation was 10 %, and the survival curve for life is shown in Figure 1. Median life expectancy following amputation was 22 months. During the 1-36 month follow-up, 9 of 48 (19 %) had a further amputation, 6 in the same leg and 3 in the contralateral leg.
1
0.8
.-> z
G
0.6
0.4
1
Om2 0 1 0
1
-
6
1
I
I
1
12
18
24
30
Months after amputation Figure 1. Life table analysis showing survival in months after amputation in 48 diabetic patients. The methodology used follows that in Kahn2'
944
There are marked differences in the incidence of lower limb amputation in diabetes populations as shown in Table 2. Many factors may contribute to this including prevalence of diabetes, resources available for diabetes care, prophylactic foot care, and vascular surgery. Our study and most of the other studies are retrospective except for the Pima Indians and Wisconsin studies.2+'o The Pima Indians have the world's highest reported prevalence of diabetes,' and this may explain why they had the highest incidence of diabetes amputation.8 Our study excluded traumatic and neoplastic causes of amputation in order to look for the amputation that related to diabetes, in contrast to the Danish and six states in USA A study in two separate parts of Sweden concluded that prophylactic foot care was the most important factor in explaining the large differences in rate of diabetes amputation in the same country,' but our data are comparable to the better Swedish region despite evidently inadequate medical management. The Danish study showed that there was an overall reduction in lower limb amputation for diabetes in Denmark from 1980 to 1989, and suggests that the time of study is also important.6 An additional variable in the calculations is the background prevalence of diabetes. If this is greater than the 1.0 % taken from elsewhere in the UK,5 then the incidence of amputation will be less than the calculated 5.7 1000-' yr-'. A further factor is the level of amputation, as 37 % of operations in our series were below ankle procedures. Our study found that 42 % of lower limb amputations were performed in diabetic patients. This is comparable with the data of previous ~tudies.~,~,' Most of the studies including our own show that incidence of diabetic lower limb amputation is higher in men (three times that in women), and that the elderly are particularly a f f e ~ t e d . ~ , ~ , ~ , 'One ~ - ' ' factor that may contribute to the male predominance is higher rates of smoking in men,15 but the precise reasons for the marked increase in amputation with age are unknown." Two studies show that there is association between amputation and longer duration of known diabetes,a,'o but no studies show data of the relationship between newly diagnosed diabetes and diabetic amputation. Our study found that, in 15 % of the amputees, the diabetes was newly diagnosed, a figure that is quite high and supports a need for increased awareness of, even screening for, diabetes in high-risk groups.18 It is also a reminder that duration from diagnosis may be very different from duration of the disease. About 38 % (16142) of diabetic amputees who had evidence of peripheral vascular disease had had angioplasty or vascular bypass surgery before amputation. This figure appears to be low, as arterial reconstruction is clearly more cost effective and successful than a m p ~ t a t i o n . 'Our ~ data showing that angioplasty was more frequent than vascular bypass surgery may be C. DEEROCHANAWONG ET AL.
DTT7
CLINICAL PRACTICE Table 2. Comparison incidence of lower limb amputation in diabetes Region and reference
Year
Incidence 1 00 000 population-' yr-'
Newcastle upon Tyne (UK) Denmark6 Denmark" Gotland (Sweden)' Umea (Sweden)' Pima Indians (USA)* Wisconsin study (USA)'O Six States (USA)*
1989-1 991 1989 1981 1971-1980 1971-1980 1972-1 984 198&1986 1976-1 978
Tayside ( S ~ o t l a n d ) ~
1980-1 982
5.7 7
Incidence 1000 diabetes-' yr-' 5.7" b
11
b
20.5 6.5 206
b
b
b b
b
13.7 5.5 5.9 10.1
"Assumes prevalence as in other parts of the UK. bData not available.
surprising, given that reconstructive surgery is usually the treatment of choice for patients with chronic limb ischaemia due to extensive obstructions.20,2' One of the recommendations of the European Consensus Group on chronic critical limb ischaemia is that no patient should undergo primary amputation without considering for reconstructive vascular surgery.lg It is unclear as to why it was felt that over half of the patients would not benefit from contrast investigation. Evidence of complete foot examination including general inspection, and assessment of peripheral nerve and vascular status before first detection of ulcer or gangrene was found in only 53 % of the diabetic amputees who were under the care of hospital diabetes clinics. This sad figure is similar to that found by other investigators.22Complete foot evaluation at least annually should lessen this problem, and certainly is a prerequisite for targeted education programmes. Two of the three hospitals in our study have the annual review clinic separate from the regular review clinic, but foot evaluation was still poor as many pre-amputees failed to attend for the annual review. There are several studies of clinical intervention that have demonstrated that proper foot care programmes may reduce the frequency of amputation among those with d i a b e t e ~ . ~ The , ~ ~ complete ,~~ programme should include identification, evaluation, and treatment of highrisk individuals, patient education, and professional education. Individuals at high risk for lower limb amputation must be identified, evaluated, and treated according to this risk status. Intervention should also cover the behaviour required for good health in the general population, including cessation of smoking, exercise, weight control, hypertension, and cholesterol control. A team approach to comprehensive foot care at the primary care level for individuals with diabetes should involve the nurse, the GP, the diabetes educator, and the c h i r ~ p o d i s t .Unfortunately ~~ our study has no data on chiropodial care and patient education. There are some data in a recent survey showing that provision of LOWER LIMB AMPUTATION IN DIABETES
chiropody services in the UK was suboptimal and hospital chiropodists have little contact with the GP.26Professional education should be aimed at all members of health care teams including those in primary health care. In our study 42 % of diabetic patients requiring lower limb amputation were under diabetes care by GPs alone, if under review at all. Thus, primary health care teams also need guidelines for identification of high-risk patients, performance of regular foot examination, and assessment of clinical risk, education, and treatment methods, and when to refer the patients for specialist care.
Acknowledgements
C. Deerochanawong was supported by a British Council fellowship. The authors are grateful to Mr J.Chamberlain, Mr N.A.G. Jones, Mr D. Lambert, Dr S.M. Marshall, Mr G. Proud, Dr R. Taylor and Dr W.M.G. Tunbridge for permitting us to look at the surgical operation records and medical records for patients under their care.
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