Evaluation of two wound measurement methods in a multi-center, controlled study

Methods for measuring wound size and healing have ranged from simple measurement with a ruler to sophisticated automated image analysis. As part of a multicenter, double-blind evaluation of a growth factor for wound healing, we evaluated the predictability and accuracy of two measurement systems. Four hundred and fifty paired comparisons (900 observation points) of lower extremity ulcers of either diabetic or venous stasis origin were evaluated weekly for at least four weeks. Wound size was determined by computer digitization of either color slide photographs (photo method) or acetate tracings (tracing method). Measurements of wound surface area for both methods were very similar, with a correlation coefficient of 0.97. The standard deviation of the methods, stratified by wound size and study center, were low (10 percent to 20 percent). Inter-site variability accounted for only 5.4 percent of the total variability noted in these observations. We have found that both the photo method and the tracing method may be useful in large, multi-center clinical trials when measurements of wound size are utilized to evaluate responsiveness to therapy.