Lack of agreement between gross visual and histological assessment of burn reepithelialization in a porcine burn model

One of the most important and earliest measures of burn healing is wound reepithelialization. Reepithelialization is a vital determinant of wound infection and scarring. Reepithelialization is generally based on gross visual assessment; however, histological assessment remains the criterion standard. We hypothesized that there would be poor agreement (r < .4) between gross visual and histological assessments of burn reepithelialization in a porcine model. The study design was prospective observational using three anesthetized female pigs (20-25 kg). Forty-eight 2.5- x 2.5-cm burns were created on the flanks of pig's using an aluminum bar (150 g) preheated to 80°C for 20 seconds. Burns were treated with an occlusive or antimicrobial dressing and photographed at day 10 for determination of gross percentage reepithelialization in a 1-cm diameter circle in the center of the burn by two experienced clinicians masked to each other's measurements. A 10-mm full-thickness punch biopsy was taken from the center of the burns and evaluated by a board-certified dermatopathologist masked to clinical assessments. One clinician and the dermatopathologist repeated the assessments 1 month apart. The outcome was percentage wound reepithelialization at 10 days. The criterion standard was the histological assessment. Intraobserver and interobserver agreements were calculated with Pearson's correlation coefficients. A coefficient less than .4 was considered poor. Sixteen burns were created on each of three animals. Six wounds were excluded because of the presence of a thick eschar covering the burn, making the gross determination of reepithelialization impossible. Intraobserver agreement for histological reepithelialization was 0.96 (P < .001). Intraobserver agreement for gross visual assessment of reepithelialization was 0.75 (P < .001). Interobserver agreement for gross visual assessment of reepithelialization was 0.60 (P < .001). The agreement between gross visual and histological assessment of burn reepithelialization was -0.25. Although there was a good interobserver agreement for gross visual assessments, there was a poor agreement between gross visual and histological assessments of burn reepithelialization. Care should be used when determining burn reepithelialization based on gross visual assessments alone.