Shoulder Pain and Disability Index: Italian cross-cultural validation in patients with non-specific shoulder pain

Background: Health-related patient reported outcome measures are considered essential to determine the impact of disease on the life of individuals. Aim of this study is to culturally adapt the Italian version of the Shoulder Pain and Disability Index (SPADI). The secondary aim is to evaluate psychometric proprieties in patients with non-specific shoulder pain. Methods: The current study is an analysis of a sample of 59 adult patients with non-specific shoulder pain. The SPADI was translated and cross-culturally adapted, and then psychometric properties were tested. Participants completed the Shoulder Pain and Disability Index-Italian (SPADI-I), 36-item short form health survey, the Oxford Shoulder Score, the Disability of Arm, Shoulder, and Hand scale and a pain intensity visual analogue scale. Results: SPADI-I included two domains. Internal consistency analysis showed good values for total (α = 0.84) and subscales (α = 0.94 and α = 0.76). For construct validity, there was good correlation between the visual analogue scale, the Oxford Shoulder Score, the DASH and the SPADI-I total score and subscales. Standard error of measurement and minimally detectable change were calculated. Conclusions: The SPADI-I was culturally adapted into Italian. SPADI-I is centred on pain and disability of the shoulder only and can be considered as a useful tool in daily clinical practice for assessing musculoskeletal non-specific shoulder pain because of its good internal consistency and validity. Further studies should focus on other psychometric proprieties such as test re-test reliability, responsiveness and clinical interpretability to improve the available clinimetrics of the tool.