Transcultural adaptation, validation and assessment of the psychometric properties of the spanish version of the Western Ontario Shoulder Instability Index questionnaire.

Abstract Objective The aim of the present study is to present a transcultural adaptation and validation of the Western Ontario Shoulder Instability Index questionnaire into Spanish (Spain), and to assess its psychometric properties. Material and methods The transcultural adaptation was conducted according to sequential forward and backward translation approach. A pilot study was subsequently performed to ensure acceptable psychometric properties. The Western Ontario Shoulder Instability Index questionnaire was administered to 79 patients twice within a period of 2 months, and patients were stratified into 3 groups (cohorts). Results ⿢ Structural validation: valid, though uneven results were obtained regarding the structure of the 4 domains of the original questionnaire. ⿢ Criterion validity: Pearson's correlation coefficient: ROWE: 0.74; EQ-5D-5L: 0.471. ⿢ Internal consistency: Cronbach's alpha: 0.96; coefficient of intraclass correlation: 0.949. ⿢ Sensitivity to change: t -Student ⿿ t : 42.38; standard response means: 2.69; effect size: 2.61; standard error of measurement: 23%; minimal detectable change: 76%. No floor or ceiling effects were detected. Conclusions The Spanish version of the Western Ontario Shoulder Instability Index questionnaire is a valid, reliable tool, and highly sensitive to change to assess patients with shoulder instability.