Independent validation of SCOPA-psychosocial and metric properties of the PDQ-39 Brazilian version

Abstract

The objective of this study was to perform an independent validation of the Scales for Outcomes in Parkinson's Disease-Psychosocial questionnaire (SCOPA-PS) and assessment of the Parkinson's Disease Questionnaire (PDQ-39), Brazilian version. Patients were evaluated by means of the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr staging (HY), Schwab and England scale, Mini-Mental State Examination, and Hospital Anxiety and Depression Scale. Health-related quality of life was evaluated using the MOS-Short Form 36 (SF-36), PDQ-39, and SCOPA-PS. One hundred forty-four patients were included (mean age, 62 years; 53.5% males; mean duration of illness, 6.6 years; HY, 1-4). Mean SCOPA-PS and PDQ-39 Summary Index (SI) were 39.2 and 40.7, respectively. The internal consistency of SCOPA-PS (Cronbach's alpha = 0.84; item-total correlation, 0.44-0.73) and PDQ-39 dimensions (alpha = 0.61-0.85; item-total correlation, 0.46-0.82) were satisfactory. Concerning the stability of the questionnaires, intraclass correlation coefficient (ICC) values were 0.71 for the SCOPA-PS and 0.86 for the PDQ-39 SI. ICC for PDQ-39 dimensions ranged from 0.52 (social support) to 0.80 (stigma). Standard error of measurement (SEM) values for each PDQ-39 dimension ranged from 0.49 (emotional well-being) to 17.52 (social support). SEM values for SCOPA-PS and PDQ-39 SI were 11.84 and 6.72, respectively. A significant correlation of SCOPA-PS and PDQ-39 SI with the SF-36 physical (-0.42 and -0.52, respectively) and mental components (-0.41) was found. Correlation between SCOPA-PS and PDQ-39 SI was 0.73 (all coefficients, P < 0.0001). The SCOPA-PS and PDQ-39, Brazilian versions, have satisfactory metric attributes.