A multicentre study of percentage change in venous leg ulcer area as a prognostic index of healing at 24 weeks

Venous leg ulcers, which may take months to heal, account for 40-70% of all lower extremity chronic wounds. New treatment options for venous leg ulcers have recently been proposed, and therefore deciding which patients are candidates for these novel-and often expensive- treatments is an important task. Moreover, researchers conducting clinical trials often wish to enrol patients who are unlikely to heal in order to minimize sample sizes needed and research costs. Our purpose was to assess the use of percentage change in venous leg ulcer area over the first few weeks of treatment as a prognostic indicator of healing or non-healing at 24 weeks. We conducted a cohort study based on an existing data set from a multicentre randomized clinical trial that enrolled 104 patients. Wounds were measured using digital planimetry for 4 consecutive weeks following the inception of good wound care. Utilizing the Wilcoxon rank sum (Mann-Whitney) test, we found that percentage change in area over time distinguished between those who healed and those who failed to heal after 24 weeks of good wound care (P < 0.05). The rate of healing, or area healed per week, did not differentiate between those who healed at 24 weeks and those who did not, as all patients had similar rates of healing over the first weeks of treatment, Percentage change in area from baseline to week 4 provided the best combination of positive and negative predictive values (68.2%, 74.7%) and the largest area under the receiver operating characteristic curve (0.75). Thus, percentage change in area over the first 4 weeks of treatment represents a practical and predictive measure of complete wound healing by 24 weeks.