Seasonal variations in lower extremity amputation.

The purpose of this study was to examine seasonal variations in nontraumatic amputation among diabetic and nondiabetic adults. We abstracted data from a database supplied by the state of New York for 14,555 amputations performed in 1990 and 1991. We categorized amputations into three different levels (foot, leg, and thigh). The most common season for a patient with diabetes to receive a lower-extremity amputation was spring (27.0%, p < 0.004; odds ratio 1.1, confidence interval 1.0 to 1.2), while winter was the most common in nondiabetic patients (27.3%, p < 0.005; odds ratio 1.1, confidence interval 1.0 to 1.2). When stratified by amputation level, fewer amputations at the level of the foot occurred during winter in patients with diabetes compared with those without diabetes (24.5% vs. 28.2%, p < 0.002; chi 2MM = 193.1, odds ratio = 1.2, confidence interval = 1.1 to 1.4). Fall was the least common season for amputation at nearly every level for both diabetic and nondiabetic groups, and more diabetic patients presented with an admission diagnosis of vascular disease (74.6% vs. 54.9%, p < 0.0001; chi 2MM = 612.3, odds ratio = 2.4, confidence interval = 2.3 to 2.6). In most diabetic patients, a primary etiologic factor for amputation is an infected neuropathic ulceration brought about or exacerbated by increased activity. By limiting activity, cold weather should act as a protective measure. The data in this study seem to support this notion.