Psychometric properties of the SCOPA-AUT Brazilian Portuguese version

Abstract

Cross-cultural adaptation and psychometric assessment of the Scales for Outcomes in Parkinson's Disease-Autonomic questionnaire (SCOPA-AUT) Brazilian Portuguese version. 150 consecutive Parkinson's disease (PD) patients were evaluated by means of the SCOPA-motor scale (SCOPA-M), SCOPA-cognition (SCOPA-COG), Hoehn and Yahr staging (H&Y), nonmotor symptoms scale (NMSS), PD questionnaire (PDQ-39), and SCOPA-AUT. The following psychometric attributes were explored: acceptability, scaling assumptions, reliability, precision, and construct validity. Patients' age (mean +/- standard deviation) was 63.1 +/- 11.1 years (56.7% men; duration of disease, 8.7 +/- 5.3 years; median H&Y, 2). Mean SCOPA-AUT was 23.0 +/- 11.2. SCOPA-AUT did not show floor or ceiling effect. As a whole, the SCOPA-AUT item-domain correlation was satisfactory, except for items 2 (Saliva), 7 (Faecal incontinence), 16 (Syncope), and 19 (Cold intolerance) (|r(S)| = 0.03-0.32). Internal consistency was adequate, except for thermoregulatory and cardiovascular domains (alpha coefficients, 0.56 and 0.63, respectively). Intraclass correlation coefficient for the total score was 0.71, whereas weighted kappa for individual items ranged from 0.15 to 0.71 (only items 4 and 7 were <0.40). Standard error of measurement was 6.04. The SCOPA-AUT total score correlated closely with the NMSS total score (r(S) = 0.65) and PDQ-39 Summary Index (r(S) = 0.61) and at a moderate level with H&Y staging (r(S) = 0.35) and SCOPA-MS total score (r(S) = 0.39) (all r(S) values, P < 0.0001). Correlation of SCOPA-AUT with SCOPA-COG was weak. SCOPA-AUT significantly increased as the H&Y stage increased (Kruskal-Wallis, P < 0.0001). The SCOPA-AUT Brazilian Portuguese version is an acceptable, reliable, and valid questionnaire to evaluate autonomic dysfunction in PD.