Development a New Scale for Assessment Shoulder Problems

The purpose of this study is to develop and psychometrically validate the Shoulder Problems Assessment Scale (SPAS), a culturally grounded patient-reported outcome measure designed to assess shoulder-related functional limitations in Turkish adults using a hierarchical stepwise yes/no response format. SPAS items are structured as four ordered difficulty thresholds for common daily activities, allowing respondents to indicate the point at which difficulty first begins while keeping the response task cognitively simple. Scale development followed a four-stage process including literature review, semi-structured patient interviews, expert content validation (Lawshe method), pilot testing, and main field testing in multiple physical therapy units across Turkey. In the main application, SPAS was administered to individuals with shoulder problems and evaluated for construct validity using exploratory and confirmatory factor analyses, reliability using internal consistency and test-retest intraclass correlation coefficients (3-7 days), and concurrent validity through correlation with the Shoulder Pain and Disability Index (SPADI). Receiver operating characteristic (ROC) analysis was performed to derive a clinically interpretable SPAS cut-off value using a SPADI-based functional limitation reference. The study aims to provide a valid, reliable, practical, and culturally appropriate PROM that can be used in routine clinical assessment and research in Turkey.