Development a New Scale for Assessment Shoulder Problems

This study was designed to develop and psychometrically validate the Shoulder Problems Assessment Scale (SPAS), a patient-reported outcome measure intended to assess shoulder-related functional limitations in adults. SPAS was developed to address limitations of existing shoulder scales related to cognitive burden, cultural relevance, and response format, particularly in populations with varying health literacy levels.

The development process followed a four-stage methodological framework. In the first stage, the conceptual framework and initial item pool were established through a comprehensive literature review, semi-structured interviews with patients experiencing shoulder problems, and input from experienced physical therapists. These steps aimed to identify daily activities that commonly provoke functional difficulty in routine life. An initial pool of 34 items was generated, including activity-based items structured in a hierarchical stepwise yes/no format.

In the second stage, content validity was evaluated by an expert panel using the Lawshe method. Items with insufficient content validity or conceptual overlap were revised, combined, or removed. A pilot study was then conducted to assess item clarity, cultural appropriateness, and comprehensibility. Based on expert feedback and pilot results, the item pool was refined and prepared for the main application.

The third stage consisted of a multicenter field application conducted in physical therapy units across multiple regions of Turkey. SPAS was administered to individuals with shoulder problems, followed by the Turkish version of the Shoulder Pain and Disability Index (SPADI) for concurrent validity assessment. A subgroup of participants with stable clinical status completed SPAS again after 3-7 days to evaluate test-retest reliability.

In the final stage, psychometric analyses were performed. Construct validity was examined using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) with a robust diagonally weighted least squares estimator appropriate for the hierarchical response structure. Reliability was assessed using internal consistency coefficients and intraclass correlation coefficients. Concurrent validity was evaluated through correlations with SPADI scores. Receiver operating characteristic (ROC) analysis was conducted to determine a clinically interpretable cut-off value for SPAS using a SPADI-derived functional limitation reference.

SPAS consists of 12 activity-based items, each comprising four ordered difficulty levels. Respondents indicate the level at which difficulty first appears, reflecting a threshold-based approach to functional limitation rather than graded symptom intensity. Total scores range from 0 to 48, with higher scores indicating greater functional limitation. The study aims to provide a valid, reliable, and practical instrument for assessing shoulder-related functional limitations in clinical and research settings.

Inclusion criteria

Adults aged 18-80 years Presence of shoulder-related pain and/or functional limitation Referred to or receiving treatment in a physical therapy or rehabilitation unit Ability to understand and respond to the questionnaire items Provision of written and verbal informed consent

Exclusion criteria

Neurological disorders affecting upper extremity function Systemic inflammatory or rheumatologic diseases involving the shoulder Severe cognitive impairment or psychiatric conditions that may interfere with questionnaire completion Acute trauma or fracture of the shoulder region requiring emergency management Incomplete or incorrectly completed questionnaire forms