Survival rates in dysvascular lower limb amputees

Abstract

Background To assess the 5-year and 10-year survival rates of major (above ankle disarticulation level) dysvascular lower limb amputees attending a sub-regional Disablement Services Centre (DSC) specialising in amputee rehabilitation. Also to investigate the association between survival rates, cause of dysvascularity, level of amputation, smoking status and occupational status. Setting The study was undertaken in sub-regional DSC for amputee rehabilitation covering a base population of about 3.5 million people. Over 80% of lower limb amputations were done for dysvascularity (peripheral vascular disease, diabetic or combination). All these patients were followed up in the DSC for their prosthetic/amputee rehabilitation. Modular case records of 201 consecutive patients from 1994 to 1995 who had diagnosis of dysvascularity as the cause of major lower limb amputations, were scrutinised regarding their 10-year survival; demographic details, level of lower limb amputations, Above Knee (AK = Transfemoral), Below Knee (BK = Transtibial), smoking status, occupational status, healing of the stump at first assessment, cause of amputation and association of these factors with survival rates. Results Of 201 individuals with either AK or BK amputations, 60% (121) had AK amputations and 67% (134) were males, the mean age was 69 years of age. Sixty-seven percent (97) had history of smoking, either current 43% (62) or prior 24% (35) smoking, and 59% (68) were skilled or non-skilled manual workers. Fifty-one percent (99) had diagnosis of peripheral vascular disease, whilst 34% (65) had combination of peripheral vascular disease and diabetes, diabetes on its own in 4% (7). In 12% (23) other causes were noted such as embolism, acute ischaemia, venous ulcers, etc. Regarding stumps healing at first assessment, healing was noted in 54% (109) whilst stump was unhealed in 46% (92). The median survival was 48 months. Using Cox proportional hazards regression to identify association with survival, the hazard ratio (HR) was significant regarding level of amputation: HR 2.34; 95% confidence interval (CI) (1.58, 3.47), P < 0.001 (a recent BK amputation increases the risk by 2.3 compared to a recent AK amputation in diabetic cohort and also in the peripheral vascular disease/diabetes cohort). Hazard ratio was less than 1.0 in bilateral amputees: HR 0.35, 95% CI (0.21, 0.60), P < 0.001 (bilateral amputation decreases risk by 0.35). Conclusion Our study indicates that the median survival remains at 4 years, which is similar to the previously published evidence in the Finish study of 1998 and the earlier study from Scotland in 1992. Unlike the previous data, our study indicates that patients with BK amputations have a higher hazard ratio than the AK amputees, and an association with diabetes has poorer prognosis regarding survival.