Shoulder Pain and Disability Index: validation of Slovene version

The objective of this study was to translate the Shoulder Pain and Disability Index (SPADI) into Slovene language and assess its reliability and validity. A total of 52 participants with shoulder problems participated in the study. They filled in the questionnaire three times: at the first visit, after 2-7 days, and at the end of the therapy. Severity of perceived disability was self-rated on a four-point scale and passive shoulder range of motion was taken at the first and the last visit. Test-retest reliability and internal consistency of SPADI were tested by intraclass correlation coefficient and Cronbach's alpha, respectively. Construct validity was evaluated using principal components analysis. Nonparametric group comparison was applied to assess criterion validity and standardized response mean calculations to evaluate responsiveness. The instrument demonstrated high test-retest reliability (intraclass correlation coefficient SPADI 0.94, pain subscale 0.89, and disability subscale 0.95) and high-to-moderate internal consistency (Cronbach's alpha SPADI 0.92, pain subscale 0.78, and disability subscale 0.90). Principal components analysis without rotation proved construct validity of the total SPADI; varimax rotation yielded two factors with little support for separation into pain and disability dimensions. SPADI proved sensitive to differences in patients' ratings of perceived disability (P<0.001). Standardized response mean values were high (SPADI 2.19, pain subscale 1.83, and disability subscale 1.92) for patients experiencing improvement. The Slovene version of SPADI is a reliable and valid instrument. Support for separation into two dimensions is lacking, so we recommend the use of total SPADI score only.