Quality of life in Parkinson's disease patients: validation of the Short-Form Eight-item Parkinson's Disease Questionnaire (PDQ-8) in Taiwan.

This study sought to evaluate the Chinese version of the eight-item Parkinson's Disease Questionnaire (PDQ-8), through standard psychometric techniques. A cross-sectional study was conducted on 100 Parkinson's disease patients attending a Movement Disorders Unit. Neurologists' assessments were based on Hoehn and Yahr, Schwab and England and Unified Parkinson's Disease Rating Scales. Patients' self-evaluations included the Taiwanese Depression Questionnaire, the 39-item Parkinson's Disease Questionnaire (PDQ-39) and PDQ-8, pain, and Pittsburgh Sleep Quality Index. Analyses for internal consistency, inter-rater reliability, and construct validity were performed. There was no evidence of floor or ceiling effects. The alpha coefficient was 0.81. Correlation of social support and bodily discomfort with the PDQ-8 was modest (0.46 and 0.36, respectively). PDQ-8 convergent validity with the PDQ-39 was very high (r = 0.96), and known-groups validity proved satisfactory. The results of this study suggest the PDQ-8 is a valid and reliable disease-specific health-related quality-of-life instrument for Parkinson's disease in Taiwan when used independently of the PDQ-39.