Translation of the Shoulder Pain and Disability Index and psychometric evaluation of the Swedish version

The Shoulder Pain and Disability Index (SPADI) is a widely used shoulder-specific patient-reported outcome measure. This study aimed to translate and adapt SPADI into Swedish, to evaluate psychometric properties and determine the minimal important change (MIC) in patients with subacromial pain.

This study was conducted in 2 phases. Phase 1 involved translation and adaptation to Swedish using forward-backward translation and patients' feedback. In phase 2, 158 patients, with shoulder pain and disability due to subacromial pain, were recruited to evaluate validity, reliability, responsiveness and MIC.

There were no disagreements during the translation process, and patients found the questions relevant and comprehensible. The SPADI and 7-item Disabilities of the Arm, Shoulder, and Hand scores showed a high correlation (0,86). Internal consistency with Cronbach's alpha 0,93 (n = 158). Test-retest reliability with Intraclass Correlation Coefficient 0,87, (n = 60). The standard error of measurement was 3,8 and the minimal detectable change was 10,5 in the total score. Responsiveness had an area under the curve of 0,92 (95% confidence interval 0,9 to 1) generating a MIC of 11, with sensitivity at 92% and specificity at 75% (n = 107).

The SPADI was successfully translated and adapted into Swedish and demonstrated excellent psychometric properties in patients with subacromial pain. Additionally, MIC values have been established to identify clinically meaningful changes, useful in both research and clinical practice. These findings support its use in this population, while further research should confirm validity for other shoulder conditions.