THU0752-HPR Development of the “treatment beliefs in knee and hip osteoarthritis (TOA)” questionnaire

Background Use of non-surgical treatment modalities in osteoarthritis (OA) is suboptimal1, which might be influenced by patients9 beliefs about treatments. An instrument for measuring treatment beliefs in OA is not available yet. Objectives To develop a questionnaire assessing patients9 beliefs about treatment modalities of hip and knee OA: the “Treatment beliefs in OA (TOA) questionnaire” and to evaluate its clinimetric properties. Methods The item pool, drawn from two previous qualitative studies, comprised beliefs regarding 5 treatment modalities: physical activity, pain medication, physiotherapy, injections and arthroplasty. A draft questionnaire comprising beliefs on these 5 treatment modalities was developed (200 items, Table 1). Two samples of patients with knee or hip OA (N=840, N=700) were recruited from our hospital to test the clinimetric properties of the TOA questionnaire. Descriptive analyses, explorative factor analyses (EFA; sample 1) and confirmatory factor analyses (CFA; sample 2) were conducted for each treatment module separately. Internal consistency was assessed with Cronbach9s Alpha (both samples). In order to examine test-retest reliability a subsample of sample 2 (N=67) was asked to fill out the final TOA questionnaire again after two weeks. Results 351 patients filled out the draft TOA questionnaire (sample 1), 289 patients filled out the final TOA questionnaire (sample 2), with a subsample (N=50) who filled out the final questionnaire twice. EFA yielded a two factor solution for each treatment modality. The factors were labeled “positive treatment beliefs” and “negative treatment beliefs”. The final TOA questionnaire comprised 60 items; items per treatment modality ranged from 9 to 14. CFA showed adequate fit indices for physical activities and physical therapy, while fit indices for the treatment modalities pain medication, injections and arthroplasty just failed to reach adequate cut-off values. Internal consistency was good to excellent for the subscale positive treatment beliefs (Cronbach9s α between 0.84 and 0.90), and mediocre to acceptable for the subscale negative treatment beliefs (Cronbach9s α between 0.66 and -0.79). Test-retest reliability was satisfactorily to good with ICCs from 0.66 to 0.88 and SEMs from 0.17 to 0.52. Conclusions The TOA questionnaire is the first questionnaire assessing positive and negative beliefs regarding five treatment modalities for knee and hip OA. The TOA questionnaire showed moderate structural validity and good internal consistency and test-retest reliability. The TOA questionnaire is useful for a better understanding of patients9 treatment beliefs. Future research will examine how treatment beliefs, in interaction with other variables, influence treatment choices. References Churchill 2016. The development and validation of a multivariable model to predict whether patients referred for total knee replacement are suitable surgical candidates at the time of initial consultation. Can J Surg, Vol. 59, No. 6, pp. 407–414. Disclosure of Interest None declared