The relation between offloading adherence and ulcer healing

The majority of diabetic foot ulcers require offloading, to reduce plantar pressure and to heal the ulcer. Non-removable offloading devices are the gold standard, and advocated as such in Australian and international guidelines. However, non-removable offloading devices can be contra-indicated, and it is reported that both clinicians and patients frequently choose removable alternatives for other reasons as well. Adherence to a removable device is crucial, but surprisingly limited research is available that actually investigates this.

New research has been published in Diabetes Care, presenting results on a subset of a large US/UK based trial. Adherence to removable offloading devices was measured using comparison between a hidden activity monitor and a hip-worn activity monitor. In multivariate analysis, Crews and colleagues report better 6-week outcomes in ulcer size reduction in patients: with smaller ulcers at baseline, treated in the UK, and being more adherent to their device. Adherence was more frequent in patients with: larger and more severe ulcers at baseline, more severe neuropathy, and greater foot pain, while postural instability predicted worse adherence.

This study confirms our thoughts that greater adherence relates to better ulcer-related clinical outcomes. It also shows that postural instability is indeed an important factor related to non-adherence, and is something to assess in clinical practice when offloading devices are handed out.

However, some caution is needed in the interpretation of these results. The first limitation is choosing ulcer area reduction at 6 weeks as primary outcome, rather than ulcer healing at 12 weeks. The importance of choosing actual healing outcomes rather than such a surrogate outcome was stressed in the recently published “reporting standards for diabetic foot ulcer studies” (see our latest research page on that paper). Further, the results presented in the paper are limited, especially with regard to the multivariate analyses, where only beta coefficients are given. Results concerning group differences in adherence would greatly enhance our understanding. For example, what was the difference in adherence between the removable devices used, between large and small ulcers, between the US and the UK, etc. It is difficult to place the findings in perspective without this information.

In conclusion, it is great to see new research on the relation between offloading device adherence and ulcer healing. This study confirms our thoughts on the importance of adherence, but many questions on the intricacy of this relation remain unanswered.