Significance: Percent area reduction (PAR) is commonly reported in trials including diabetic foot ulcers (DFUs) and venous leg ulcers (VLUs). It is unclear how well PAR performs as a surrogate marker for complete wound closure. This review aimed to summarize all available evidence evaluating PAR as a predictor of complete DFU and VLU healing. Recent Advances: A review searching the CENTRAL, MEDLINE, EMBASE, and EMCARE databases was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Randomized-controlled trials and observational studies reporting PAR and any measure of its predictive ability were included. Outcomes included performance measures of PAR, timing of PAR, outcome measurement, and specific PAR cutoffs. Critical Issues: Meta-analysis was not possible due to high variability in wound duration at study start (2-48 weeks), PAR timing (2-8 weeks), PAR cutoff (-3% to 90%; determined post hoc in most studies), and outcome assessment (10-24 weeks). Six studies (21,430 DFU patients) report PAR as having acceptable to outstanding discriminatory ability (C-statistic 0.720-0.910). Five studies (29,775 VLU patients) report PAR as having poor to excellent discriminatory ability (C-statistic 0.680-0.830). One study (241 DFU and VLU patients) reports PAR sensitivity and specificity of 58.5% and 90.5%, respectively. All studies were determined to have high risk of bias. Future Directions: Despite promising discriminatory ability, most studies report post hoc analysis of patients in randomized trials, are highly heterogenous in study design, and have high risk of bias. There is scant evidence to support PAR in isolation as a surrogate for complete DFU or VLU healing in routine clinical practice.
Keywords: diabetic foot ulcer; percent area reduction; surrogate marker; venous leg ulcer.