Spanish cultural adaptation and validation of the shoulder pain and disability index, and the oxford shoulder score after breast cancer surgery.

Background: The Oxford Shoulder Score (OSS) and the Shoulder Pain and Disability Index (SPADI) are patient-based outcome scores with valid psychometric properties which are widely used for shoulder interventions.

Objective: The purpose of the study is to adapt both questionnaires cross-culturally to Spanish, and to test their reliability, validity, responsiveness, and feasibility.

Design: Cultural adaptation and psychometric validation study.

Methods: Consecutive patients who had undergone breast cancer surgery referred to an outpatient clinic at the University of Alcalá de Henares, Spain. One hundred and twenty women who had undergone breast cancer surgery, with pain and shoulder dysfunction. Cross-cultural adaptation was performed according to the international guidelines. Reliability was analysed by test-retest reliability and internal consistency. Content and convergent construct validity were measured by the Expert Committee's and Spearman coefficient respectively. Responsiveness, feasibility, floor and ceiling effects were also tested.

Results: One hundred and twenty women aged 54.2 (±11) years took part in the study. The reliability was excellent; test-retest reliability was 0.974 (p < 0.001) for OSS, and 0.992 (p < 0.001) for SPADI; and Cronbach's alpha value was 0.947 for OSS, and 0.965 for SPADI. High construct validity was found between the OSS and SPADI questionnaires (r = -0.674). The effect size (ES) and standardized response mean (SRM) was moderate in OSS (ES = 0.50 and SRM = 0.70 (p < 0.001)), and moderate to good in SPADI (ES = 0.59 and SRM = 0.82 (p < 0.001)).

Limitations: This study has some limitations, such as the group of participants is composed only of women following breast cancer treatment; the measurement took place in a single centre; and all the questionnaires administered were always provided to the participants in the same order.

Conclusions: The OSS and SPADI Spanish versions are applicable, reliable, valid, and responsive to assess shoulder symptoms and quality of life in Spanish women with shoulder pain and disability after breast cancer treatment.