Use of photographs for the identification of pressure ulcers in elderly hospitalized patients: validity and reliability

To evaluate the ability of research nurses to identify pressure ulcers, the authors assembled digital photographs of the skin of 160 consenting elderly patients (80% African American, 63% women). The series included 39 photos of pressure ulcers, 109 of normal skin, and 12 of other skin conditions, determined by consensus by two experts (D.J.M. and S.H.K.). Photos were packaged electronically into eight blocks of 20, with pressure ulcer prevalence ranging from 20% to 30% per block. The eight blocks were duplicated to create two sets of 160 photos each. Each of six raters (experienced clinical research nurses), working independently, evaluated the 320 photos as if each photo depicted a different patient. For analysis, the ratings were collapsed into binary determinations (any pressure ulcer vs. none). The overall sensitivity and specificity of the ratings were 0.97 (95% confidence interval: 0.94, 0.98) and 0.81 (95% confidence interval: 0.77, 0.86), respectively. Rater-specific prevalence (range: 31.8-47.5%) exceeded the true prevalence (24.4%). Inter- and intrarater reliability coefficients were 0.69 and 0.84, respectively. Trained research nurses can accurately classify pressure ulcers from photographs, even when patients are largely non-White and the photographs depict pressure ulcers spanning all pressure ulcer stages.