Lower Extremity Amputation Rates in People With Diabetes Mellitus: A Retrospective Population Based Cohort Study in Zwolle Region, The Netherlands.

Objective: Lower extremity amputations are a major complication of diabetes mellitus (DM). In a previous Dutch study, the incident rate of major amputations was 89.2 per 100 000 person years. The primary aim of this study was to describe the lower extremity amputation rates in people with DM in the Zwolle region, where preventive and curative footcare is organised according to the guidelines of the International Working Group of the Diabetic Foot (IWGDF). The secondary aim was to evaluate outcomes and underlying characteristics of these people.

Methods: This was a retrospective regional population based cohort study. Data from all people with DM treated in primary and secondary care, living in the region Zwolle were collected. All amputations in the period 2017 to 2019 were analysed. Comparisons were made between those with and without an amputation.

Results: In the analysis 5 915 people with DM were included, with a mean age of 67.8 (IQR 57.9, 75.9) years. Of those people, 47% were women and the median HbA1c was 53 (IQR 47, 62) mmol/mol. Over the three year study period 68 amputations were performed in 59 people: 46 minor, 22 major. This translated into an average annual crude amputation incidence rate of non-traumatic major and minor amputations of 41.5 and 86.9 per 100 000 person years among people with diabetes. Compared with those not undergoing amputations, those who underwent an amputation were more often men, older, mainly had T2DM, were treated in secondary care, had higher diastolic blood pressure, worse diabetic footcare profile, longer DM duration and higher HbA1c. At the end of the follow up, 111 people died: 96 (1.6%) without and 15 (25.4%) with amputations (p < .001).

Conclusions: This retrospective study provides detailed insight into the rate of amputations in Dutch people with diabetes in the region Zwolle. Compared with previous Dutch estimates, these data suggest a considerable decrease in the major amputation incidence rate.