Validation and Clinimetric Properties of Persian Version of the <scp>ISTAP</scp> Classification System

Skin tears (ST) are common traumatic wounds, particularly among older adults, that can lead to complications if not accurately assessed and classified. The International Skin Tear Advisory Panel (ISTAP) classification system is widely used internationally; however, no validated Persian version currently exists. To culturally adapt, and evaluate the clinimetric properties of the Persian version of the ISTAP Classification System. This methodological study was conducted from February to May 2025 in multiple phases. After forward-backward translation and expert review, face and content validity were assessed. Criterion validity was assessed by comparing nurses' classifications with expert consensus using weighted Cohen's kappa coefficient. Construct validity was examined using the known-groups method, comparing skin tear frequency and severity between 30 elderly patients with impaired mobility and 30 younger adults without impaired mobility. Reliability was evaluated using Fleiss' kappa coefficient for multiple raters, and weighted Cohen's kappa coefficient for inter-rater and intra-rater agreement. Diagnostic accuracy indices, including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), negative likelihood ratio (LR-), odds ratio (OR) and the area under the receiver operating characteristic curve (AUC), were calculated for each skin tear type. Content validity was excellent (content validity ratio (CVR): 0.82-1.00; item-level content validity index (I-CVI): 0.91-1.00; scale-level content validity index (S-CVI/Ave): 0.94). Criterion validity showed almost perfect agreement with experts (weighted κ = 0.902, p < 0.001). Construct validity was supported by significant group differences in skin tear frequency (Fisher's exact p = 0.001) and severity (t(58) = 2.12, p = 0.039). Reliability was substantial to almost perfect across analyses (Fleiss' κ = 0.8447; inter-rater weighted κ = 0.66; intra-rater weighted κ = 0.86). Diagnostic accuracy was excellent for all types (AUC = 0.99), with sensitivity 97.5%-99.2%, specificity 98.4%-99.6%, PPV 97.5%-99.3%, NPV 98.1%-99.6% and very high OR and LR values. The Persian version of the ISTAP Classification System demonstrated excellent validity, reliability and diagnostic accuracy, supporting its use as a standardised tool for assessing ST in Persian-speaking healthcare settings.