Aims/hypothesis: This study examined the relationship between symptoms of depression and the development of diabetic foot ulcers.
Methods: Participants were 333 patients (71% male; mean age 62 years; 73% with type 2 diabetes) with diabetic peripheral neuropathy (DPN), but without peripheral vascular disease (PVD). Severity of DPN and the presence of PVD were assessed by clinical examination. Depression, other diabetes complications and foot self-care were assessed by self-report. Cox regression tested whether depression was an independent predictor of foot ulceration over 18 months, whether this relationship was moderated by foot ulcer history, and whether foot self-care mediated this relationship.
Results: During follow-up, 63 patients developed a foot ulcer. Those with prior foot ulcers had more than four-fold greater risk of subsequent foot ulceration compared with those without a history of foot ulcer. A significant interaction effect showed that depression was significantly related to the development of first but not recurrent foot ulcers. This relationship was independent of biological risk factors. In the final model, each standard deviation increase in depression symptoms was significantly associated with increased risk of developing first foot ulcers (HR 1.68, 95% CI 1.20-2.35), while foot self-care was associated with lower risk (HR 0.61, 95% CI 0.40-0.94). Foot self-care did not mediate the relationship between depression and foot ulceration.
Conclusions/interpretation: These data suggest that depression is associated with increased risk of first foot ulcers in DPN patients and that this relationship is independent of biological risk factors and foot self-care. Interventions that target depression and foot self-care before the development of foot ulcers may maximise the likelihood of successful prevention of foot ulceration.