Risk factors for lower extremity amputation in patients with diabetic foot ulcers: a hospital-based case–control study

BACKGROUND Diabetic foot ulcers (DFU) may cause significant morbidity and lower extremity amputation (LEA) due to diabetic foot problems can occur more often compared to the general population. The purpose of the present study was to use an epidemiological design to determine and to quantify the risk factors of subsequent amputation in hospitalized DFU patients. METHODS We performed a hospital-based, case-control study of 47 DFU patients with LEA and 47 control DFU patients without LEA. The control subjects were matched to cases in respect to age (±5 years), sex, and nutritional status, with ratio of 1:1. This study was conducted in Dr. Kariadi General Hospital Semarang between January 2012 and December 2014. Patients' demographical data and all risk factors-related information were collected from clinical records using a short structural chart. Using LEA as the outcome variable, we calculated odds ratios (ORs) and 95% confidence intervals (CIs) by logistic regression. Univariate and stepwise logistic regression analyses were used to assess the independent effect of selected risk factors associated with LEA. The data were analyzed in SPSS version 21. RESULTS There were 47 case-control pairs, all of which were diagnosed with type 2 diabetes mellitus. Seven potential independent variables show a promise of influence, the latter being defined as p≤0.15 upon univariate analysis. Multivariable logistic regression identified levels of HbA1c ≥8% (OR 20.47, 95% CI 3.12-134.31; p=0.002), presence of peripheral arterial disease (PAD) (OR 12.97, 95% CI 3.44-48.88; p<0.001), hypertriglyceridemia (OR 5.58, 95% CI 1.74-17.91; p=0.004), and hypertension (OR 3.67, 95% CI 1.14-11.79; p=0.028) as the independent risk factors associated with subsequent LEA in DFU. CONCLUSIONS Several risk factors for LEA were identified. We found that HbA1c ≥8%, PAD, hypertriglyceridemia, and hypertension have been recognized as the predictors of LEA in this study. Good glycemic control, active investigation against PAD, and management of comorbidities such as hypertriglyceridemia and hypertension are considered important to reduce amputation risk.