Impact of insufficient drug efficacy of antiparkinson agents on patient's quality of life: a cross-sectional study

Background: To understand the current state of insufficient drug efficacy experienced by patients with Parkinson's disease (PD) and its effects on quality of life (QOL), we conducted a survey of patients with PD and analyzed the results from 2,630 completed questionnaires. Methods: The questionnaires inquired about age, sex, Hoehn and Yahr stage, disease duration, drugs currently being taken, and the current state of insufficient drug efficacy; it also included items of the Parkinson's Disease Questionnaire-8 (PDQ-8). Questionnaires were mailed to members of the Japan Parkinson's Disease Association. Results: Approximately 70 % of all subjects reported some type of insufficient drug efficacy, and around half of these experienced this early in the morning or at night. The proportion of subjects who experienced insufficient drug efficacy was found to increase with greater disease severity according to the Hoehn and Yahr stage. However, even among patients with stage I severity, insufficient drug efficacy was reported by approximately 40 % of the respondents. QOL was significantly lower in patients who experienced insufficient drug efficacy than in those who did not (PDQ-8 summary index; 42.0 +/- 20.1 vs. 30.0 +/- 19.5; p < 0.0001). Conclusions: These results suggest that insufficient drug efficacy might affect the quality of life of patients in most stages PD including the early stages. Therefore, greater awareness of insufficient drug efficacy gained by questioning patients might help medical practitioners in taking appropriate actions.