Risk factors for infection in patients with chronic leg ulcers: A survival analysis.

AIM: This study aimed to validate the relationships between possible predictive factors and clinically diagnosed infection in adult patients with chronic leg ulcers. METHODS: This study used a sample of 636 adult participants whose ulcers were diagnosed as either venous, arterial or mixed aetiology leg ulcers and had no clinical signs of infection at recruitment. Data were extracted from recruitment to 12 weeks from six longitudinal prospective studies from 2004 to 2015. Survival analysis was used to investigate mean time-to-infection, including the Kaplan-Meier method and the Cox proportional-hazards regression model. RESULTS: The sample included 74.7% venous, 19.6% mixed and 5.7% arterial leg ulcers. There were 101 (15.9%) participants diagnosed with infection at least once within 12 weeks of follow-up. Mean time-to-infection was 10.89 weeks (95% CI = 10.66-11.12). After adjustment for potential confounders, a Cox proportional hazards regression model found that depression, using walking aids, calf ankle ratio <1.3, wound area ≥10 cm2 and ulcers with slough tissue at recruitment were significant risk factors for wound infection. CONCLUSION: This study has validated the predictive ability of factors which have been found in a cross-sectional study to be significantly associated with infection in patients with leg ulcers, including venous leg ulcers, arterial leg ulcers and mixed aetiology leg ulcers. Results showed that patients with chronic leg ulcers, who either presented with depression, used walking aids, had a calf ankle ratio <1.3, a wound area ≥10 cm2 or an ulcer with slough tissue, had greater likelihood of developing infection compared to those without these factors.