Cost-effectiveness analysis of dopamine agonists in the treatment of Parkinson's disease in Japan

Background: Dopamine agonists such as bromocriptine or pergolide are often used in Japan to treat Parkinson's disease. Dopamine agonists are relatively expensive drugs; economic evaluations are required. Objective: To evaluate the cost effectiveness of dopamine agonists for the treatment of Parkinson's disease in Japan. Design and setting: We used a Markov model to simulate the course of Parkinson's disease and to compare the cost effectiveness of dopamine agonists added to levodopa with that of levodopa alone in Japan. The model assumed that 60-year-old men with Parkinson's disease in Hoehn-Yahr (HY) stages 2 to 5 using levodopa were administered dopamine agonists or continued on levodopa alone. The incremental cost effectiveness of dopamine agonists used for 10 years was then estimated. Study perspective: Societal. Main outcome measures and results: In the patients in HY stage 2, the incremental cost effectiveness of dopamine agonists was 18 610 000 to 19 320 000 yen (Y) per quality-adjusted life-year (QALY) [$US172300 to $US178900/QALY; 1998 values]. In patients in HY stage 3 or higher, the use of dopamine agonists was dominant over levodopa alone mainly due to reduced cost for care. In sensitivity analyses, costs and effectiveness of dopamine agonists significantly influenced the results. The use of a generic formulation of bromocriptine was dominant over levodopa alone even in the patients with HY stage 2 disease. Conclusions: Dopamine agonists appear to be cost effective in advanced Parkinson's disease, although their use is sensitive to the costs and effectiveness of dopamine agonists. If factors discouraging the prescription of generic drugs in Japan were removed, the treatment of Parkinson's disease would become more cost effective.