Objective: The Modified Parkinson Activity Scale (M-PAS) is used to identify the most important activity limitations in patients with Parkinson’s disease. We developed a Japanese version of the M-PAS and evaluated its reliability and validity.

Methods: Twenty-five patients with Parkinson’s disease (median age 71 years old, range 58–83) were enrolled, and two raters used the Japanese version of M-PAS to assess the subjects. The inter-rater reliability was evaluated using Cohen’s weighted kappa coefficient for the total score and three domain scores; systematic error was investigated using Bland-Altman analysis. Concurrent validity of the Japanese M-PAS was measured using Spearman’s rank correlation coefficients.

Results: Cohen’s kappa coefficients for the total score and the three domain scores were in the range 0.81–0.98, and 95% confidence intervals included zero for each item, suggesting excellent agreement and no systematic errors. The scores of the Japanese version of M-PAS were significantly correlated with the scores of the Movement Disorder Society–Unified Parkinson’s Disease Rating Scale Part II (Spearman’s rho=–0.56, P< 0.01) and Part III (Spearman’s rho=–0.32, P< 0.01). The percentage of patients with the highest and the lowest scores in the Japanese version of M-PAS suggested no ceiling or floor effects.

Conclusion: The Japanese version of M-PAS showed excellent inter-rater reliability and good concurrent validity without ceiling or floor effects.