Risk factors for lower extremity amputation in patients with diabetic foot ulcers: A meta-analysis

PURPOSE: A considerable number of diabetic foot ulcer (DFU) patients require amputation every year, which worsens their quality of life, aggravates the social burden, and shortens their life expectancy. Considering these negative effects, it is important to explore the relative risk factors affecting amputation in DFU patients. METHODS: The PubMed, SCIE and Embase databases were comprehensively searched for prospective or retrospective studies published before October 31, 2019. All English language studies involving DFU patients were included, and RevMan 5.3 software was used to analyse the data. RESULTS: This meta-analysis includes 21 studies involving 6505 participants, including 2006 patients who required a lower limb amputation. The following variables were associated with an increased risk of amputation: male sex (odds ratios (OR) = 1.30, 95% confidence interval (CI) = 1.16~1.46, P<0.00001), smoking history (OR = 1.19, 95% CI = 1.04~1.35, P = 0.009), a history of foot ulcers (OR = 2.48, 95% CI = 2.00~3.07, P<0.00001), osteomyelitis (OR = 3.70, 95% CI = 3.02~4.53, P<0.00001), gangrene (OR = 10.90, 95% CI = 5.73~20.8, P<0.00001), a lower body mass index (mean difference IV (MD) = -0.88, 95% CI = -1.30~-0.47, P<0.0001), and a higher white blood cell count (MD = 2.42, 95% CI = 2.02~2.82, P<0.00001). However, age (MD = 1.24, 95% CI = -0.45~2.93, P = 0.15), type of diabetes (OR = 0.96, 95% CI = 0.61~1.52, P = 0.86), hypertension (OR = 1.19, 95% CI = 0.96~1.47, P = 0.12), and HbA1c level (MD = 0.02, 95% CI = -0.28~0.33, P = 0.87) were not associated with amputation in patients with DFU. CONCLUSIONS: Our meta-analysis identified several risk factors for amputation in DFU patients, including the male sex, a smoking history, a history of foot ulcers, osteomyelitis, gangrene, a lower body mass index, and a higher white blood cell count. Once gangrene occurs, the risk of amputation rapidly increases.