THE INFLUENCE OF WOUND GEOMETRY ON THE MEASUREMENT OF WOUND-HEALING RATES IN CLINICAL-TRIALS

Purpose: The comparison of wound healing rates in clinical trials pres ents a challenging problem. Wound healing typically has been expressed as a change in area over time or a percent change in area over time. These methods are inaccurate, however, when applied to wounds of varyi ng size and shape. A relatively small amount of healing in a large wou nd will produce a greater change in area than in a smaller wound. Conv ersely, measurement of the percent change in area of a wound will tend to exaggerate the healing rates of smaller wounds. A method of calcul ating average linear healing of the wound edge toward the center of th e wound has been proposed that should not be influenced by wound size: D = Delta A divided by (P) over bar, where D = linear healing, Delta A = change in area, and (P) over bar = mean perimeter. The purpose of this study was to examine linear healing of the wound edge as a method of measuring wound healing in clinical trials. Methods: We observed 3 9 patients with venous stasis ulcers. The area, perimeter, length, and width of each wound were calculated with computerized planimetry. Cha nge in area per day and linear healing rate of the wound edge per day were calculated. Multiple linear regression analysis was used to explo re factors that influence wound healing as measured by these methods. Results: The change in area per day was significantly and independentl y influenced by initial area (p < .0001), perimeter (p < .0001), lengt h (p < .00055), and width (p < .0175). Linear healing per day was not influenced by any geometric variable, including area, perimeter, lengt h, width, and ratio of width to length. Conclusion: Linear healing per day is a valid means of comparing wound healing rates in wounds of di fferent dimensions. Linear healing per unit of time should be preferre d to measurements of change in wound area to quantify wound healing ra tes in clinical trials.