People with an infected diabetes-related foot ulcer (DFU) have a significantly increased risk of hospitalisation and amputation. Studies have reported a 25-60% prevalence of infections in people with diabetes-related foot ulcers (DFU). However, few studies have investigated the incidence and risk factors for developing infections in people with DFU. This study aimed to investigate the annual incidence and risk factors for developing infection in people initially presenting with a DFU that was not infected.
A retrospective analysis of patients initially presenting between 2012-2014 with a non-infected DFU to one of 30 outpatient High Risk Foot Services across Queensland was conducted using the Queensland High Risk Foot Form Database. Self-reported demographic, social determinant, medical history, foot disease history, past foot treatment, and, clinically-diagnosed DFU characteristics, type and management provided were captured at baseline. Participants were then followed for 12 months to determine the incidence of clinically-diagnosed foot infection. Multivariate logistic regression models were used to test for risk factors for developing infection.
Overall, 853 patients were included; mean(SD) age 63(13) years, 68.0% male, 90.9% type 2 diabetes. Foot infection developed in 40.1% of patients and there was no difference in annual incidence between DFU types (p>0.05). Independent risk factors for developing infection in patients with DFU were: deep ulcers (Odds Ratio 2.4); peripheral neuropathy (OR 1.8); previous foot ulcer history (OR 1.8); female gender (OR 1.5); and age in years (OR 0.98) (all p<0.02).
These findings suggest 40% of people presenting with a non-infected DFU will develop a foot infection in the following year, regardless of DFU type. Those developing an infection were more likely to have deep ulcers, peripheral neuropathy, previous DFU history, be female and of younger age on presentation. Further research is recommended to investigate other potential risk factors for developing diabetes-related foot infection.