Methodological considerations of investigating adherence to using offloading devices among people with diabetes.

Foot ulcers are a diabetic complication associated with significant morbidity, mortality, and amputation risk. Offloading devices prevent and heal foot ulcers, but adherence to using these devices is low. The reasons for nonadherence are unclear, and study results are difficult to compare due to methodological heterogeneity. This paper explores aspects of investigating adherence to using offloading devices among people with diabetes and provides recommendations for future studies, focusing on study designs, definitions of adherence, measurement methods, and conceptual frameworks. Most studies use a cross-sectional observational study design, limiting the potential to establish the temporal sequence between predictors and adherence, rule out confounding factors, and establish causality. Studies defining adherence as the length of time the device is worn have often used self-report to measure adherence, which may be unreliable. Studies using activity monitors to measure adherence have defined adherence as the number of steps taken with the device, which excludes weight-bearing activities where no steps are taken. Conceptual frameworks are not made explicit in the current quantitative research. It is concluded that future studies should use a longitudinal design with observational studies to identify patient groups prone to nonadherence and factors that influence adherence and experimental studies to evaluate interventions to improve adherence, focusing on these patient groups and factors. Furthermore, adherence should be defined in terms of relative adherence to using offloading devices during all weight-bearing activities, and objective measurement of adherence (using accelerometers and temperature monitors) should be used whenever possible. Clearly defined conceptual frameworks should guide the choice of factors to include in the study and the analysis of their interactions. By implementing these recommendations, research could provide a stronger evidence base in the future, supporting interventions to increase adherence and thereby improve outcomes for people with diabetic foot complications.