Psychometric properties of three different scales for subjective evaluation of shoulder pain and dysfunction in Italian patients after shoulder surgery for anterior instability

Abstract

Background: The Italian versions of Shoulder Pain and Disability Index (SPADI), Simple Shoulder Test (SST), and University of California-Los Angeles (UCLA) Shoulder Rating Scale have been validated to assess shoulder dysfunction in patients treated for neck cancer. The present study investigated the psychometric properties of the Italian versions of the SPADI, SST, and UCLA in patients after shoulder surgery for anterior instability.

Materials and methods: The study population included 98 patients. Patients completed the Italian SPADI, SST, and UCLA, and Western Ontario Shoulder Instability Index (WOSI), American Shoulder and Elbow Surgeons (ASES) Standardized Shoulder Assessment Form, Oxford Shoulder Score (OSS), and 36-Item Short Form Health Survey (SF-36). Reproducibility was assessed by asking patients to complete another UCLA, SPADI, and SST 48 hours after the first. Validity was assessed by calculating the correlation between the SPADI, SST, and UCLA and the WOSI, ASES, OSS, and the SF-36 Physical Health subscales.

Results: The internal consistencies of the SPADI (α = 0.97) and the SST (α = 0.87) were very high. The test-retest reliability was excellent with intraclass correlation coefficient of 0.97 for the SPADI, 0.93 for UCLA pain, 0.95 for UCLA function, and 0.97 for the SST. A significant correlation was found between the Italian SPADI, SST, and UCLA and the WOSI, the ASES and the OSS.

Discussion: Psychometric properties of the Italian SPADI, SST, and UCLA compared well with those reported for the original versions, supporting their use as reliable clinimetric instruments in the setting of shoulder disorders after surgery for recurrent anterior instability.

Keywords: Italian; SPADI; SST; UCLA; instability; shoulder; validation.