Abstract
BACKGROUND: Tracking wound size is an essential part of treatment. Because a wound's initial size may affect apparent healing rates, its surface area (S) and its surface area-to-perimeter (S/P) ratio are useful to document healing. Assessments of these parameters can be made by computerized planimetry of digital images using suitable software.
OBJECTIVE: Because different caregivers often evaluate wounds and because measurement time is important, the objective of this study was to determine accuracy, repeatability, and measurement time of S and S/P from measurements of images recorded by digital photography.
METHODS: Six wound images of various complexities with known areas were measured in triplicate by 20 senior nursing students during 2 sessions 1 week apart. Images included an ellipse, 2 traced venous ulcers, and photographs of a pressure, diabetic plantar, and venous ulcer. Area error was determined as the percentage difference between known and planimetry measured areas. Reliability was assessed from test-retest coefficient of variations (CV%) from which the smallest meaningful percentage change (SMPC) was determined.
RESULTS: Area errors (mean +/- SD) ranged from -2.95% +/- 7.01% to +2.32% +/- 6.04%. For well-defined image margins, area and S/P SMPC values were all less than 3.2%. For borders that were not as well defined, SMPCs were larger, ranging between 6.2% and 10.8%. Wound measurement time decreased from 93.4 +/- 35.1 seconds at session 1 to 67.7 +/- 24.4 at session 2 (P < .001).
CONCLUSIONS: Results based on the specific software used and on the outcomes of the study group indicate that simple computer-based planimetry of digital images can provide rapid, accurate, and reliable estimates of wound area and S/P ratios.