Western Ontario Osteoarthritis Shoulder (WOOS) index: a cross-cultural adaptation into Swedish, including evaluation of reliability, validity, and responsiveness in patients with subacromial pain

BackgroundThe aim of the present study was to translate the Western Ontario Osteoarthritis Shoulder (WOOS) index into Swedish and to test its validity, reliability, and responsiveness in patients with subacromial pain.MethodsThe validity of the WOOS translation was tested in 54 patients who completed the WOOS and the Shoulder Rating Questionnaire, Swedish version (SRQs). Of these patients, 46 were retested to assess reliability. Responsiveness was evaluated in 29 subjects who completed the WOOS and SRQs before surgery and again at 3 months after surgery, when they also rated perceived change in shoulder function. The relationship between the questionnaires and patient-perceived improvement was assessed.ResultsA high correlation was found between the Swedish version of WOOS and the SRQs. The correlations were similar in a group of working patients (r = −0.832) and in all patients (r = −0.843; P < .001). A high degree of agreement between WOOS at test and retest was also observed. A Bland-Altman plot showed a small mean difference and no trend across the range of WOOS values. A strong significant agreement was also shown by a κ value of 0.649 (P < .001) and an intraclass correlation coefficient of 0.95 (95% confidence interval, 0.92-0.97, P < .001) as well as by a low difference between the test and retest means. Responsiveness, calculated by standardized response mean, was excellent (1.02).ConclusionThe results of the present study provide evidence that the Swedish version of WOOS is valid, reliable, and responsive in patients with subacromial pain and performs similarly to the original Canadian version.