Effect of limb preservation status and body mass index on the survival of patients with limb-threatening diabetic foot ulcers.

To evaluate the effect of limb preservation status and body mass index (BMI) on the survival of patients with diabetic foot ulcers (DFUs).

A total of 1346 patients treated for limb-threatening DFUs at a major diabetic foot center in Taiwan from 2002 to 2009 were tracked until December 2012. The patients were classified into three groups: limb-preserved (n=858), minor lower-extremity amputation (LEA) (n=249), and major LEA (n=239). Clinical data during treatment were used for survival analysis.

With 729 deaths, the median survival time (MST) was 6.14 (95% CI 5.63-6.65) years. Major LEA and BMI were two independent factors associated with mortality after adjusting for age, diabetic duration, HbA1c level, comorbidities and peripheral artery diseases. The mortality hazard ratios for the minor and major LEA groups were 0.92 (95% CI 0.74-1.16) and 1.34 (95% CI 1.07-1.68), respectively, to the reference group (limb-preserved). After stratifying BMI into four categories (underweight, normal weight, overweight and obesity, according to the Taiwanese definition), the MSTs for each category were 2.57, 5.24, 7.47 and 7.85years, respectively (P for trend <0.01). This "obesity paradox" was not observed in the major LEA group (P for trend 0.25). For patients with LEA, the obesity patients had lower MST than those in overweight category (7.97 and 8.84 in minor and 3.25 and 5.42 in major LEA, respectively).

For the patients treated for DFUs, major - but not minor - LEA was associated with poor survival compared with the limb-preserved group. The MST had positive correlation with BMI levels for patients with limb-preserved and minor LEA, but not for those with major LEA.