Cross-cultural adaptation, validation, and reliability of the Italian version of the patient and observer scar assessment scale (POSAS-I) version 3.0.

Vercelli, Stefano; Razza, Simona; Laurelli, Dario; Negrini, Francesco; Bravini, Elisabetta; Ferriero, Giorgio · Disabil Rehabil · 2025

cross_sectional · Level IV

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Abstract

The Patient and Observer Scar Assessment Scale (POSAS) is one of the most comprehensive scar assessment tools worldwide. Version 3.0 represents a significant enhancement, yet lacks psychometric validation. To translate, culturally adapt, and validate the POSAS 3.0 Italian version (POSAS-I 3.0) in subjects with post-surgical scars. The POSAS 3.0 was translated into Italian following international guidelines. A hybrid approach incorporating both formative model validation (collinearity and relevance of indicator weights) and classical test theory methods (hypothesis testing for construct validity, reliability, measurement error, floor/ceiling effects, and acceptability) was employed to provide evidence for clinical application. A total of 115 scars were included. The POSAS-I 3.0 demonstrated excellent construct validity with strong correlations between OSAS-I/PSAS-I vs Vancouver Scar Scale (VSS) (r<sub>s</sub> = 0.88 and r<sub>s</sub> = 0.68, respectively), and OSAS-I vs PSAS-I (r<sub>s</sub> = 0.61). Both sub-scales showed excellent reliability (ICC > 0.92) with minimal measurement error (SEM = 3.5% OSAS-I, 1.4% PSAS-I). Floor and ceiling effects were below the critical threshold of 15%. The scale demonstrated good acceptability with reasonable completion times. The POSAS-I 3.0 is a valid, reliable instrument for post-surgical scar assessment in Italian clinical and research settings, representing the first validated POSAS 3.0 version in any language.