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As recommended by the guidelines such as JSH 2004, combination therapy with multiple agents is now being applied to many patients with hypertension. However, a pharmacoeconomic analysis of each therapy has not been fully undertaken in Japan, despite increasing societal interest. In this study, the cost-effectiveness of two calcium channel blockers, each coadministered with an angiotensin receptor blockade, was compared using data from the ADVANCE-Combi study. The ADVANCE-Combi study was a 16-week double-blind, randomized clinical trial to compare the efficacy and safety of two combination therapies (controlled-release nifedipine [nifedipine CR] plus valsartan vs. amlodipine plus valsartan) on blood pressure (BP) control in patients with moderate to severe essential hypertension. The incremental cost effectiveness of each cohort was compared from the perspective of insurers. The average total cost per patient was Japanese yen (JPY) 31,615 for the nifedipine CR treatment group and JPY 35,399 for the amlodipine treatment group (p < 0.001). The achievement rate of the target BP (SBP/DBP < 130/85 mmHg for patients aged under 60 years; SBP/DBP < 140/90 mmHg for those aged 60 years and over) was significantly higher in the nifedipine CR treatment group (61.2%) than in the amlodipine treatment group (34.6%) (p < 0.001), with no difference in the incidence of drug-related adverse events. Accordingly, the base case economic analysis demonstrated that the nifedipine CR treatment group was dominant (more efficacious and less costly) to the amlodipine treatment group. This result was supported by univariate and probabilistic sensitivity analyses. These results indicate that nifedipine CR-based combination therapy is superior to amlodipine-based combination therapy for the management of essential hypertension in the Japanese population.

Hypertension is prevalent in over 25% of populations in developed countries, and poses an increasing economic burden on health resources. Therefore it is predicted that future medical treatment of hypertension will be increasingly affected by cost considerations. Several classes of antihypertensive drugs are used as first-line agents for the treatment of hypertension, but the economic impact of using these agents in different countries remains to be addressed. In this study, we compared health costs associated with treatment of hypertension using the calcium channel blocker amlodipine and the angiotensin-converting enzyme inhibitor enalapril in the US and Japan. Pharmaceutical costs and hospitalization costs were analyzed from established databases. The data for the prevalence of myocardial infarction and stroke were derived from the Framingham study and the Hisayama study. Analysis of the economic impacts using relative risk differences between the calcium channel blocker and angiotensin-converting enzyme inhibitor together with regional hospitalization costs resulted in an apparent 11.2 billion yen health cost reduction in favor of the calcium channel blocker in the case of Japan, in contrast to an apparent 5.7 billion yen reduction in favor of the angiotensin-converting enzyme inhibitor in the case of the US. The trends in Japan for 2000 and 2004 were similar. These results suggest that there are regional differences in the health costs associated with different classes of hypertensive agents, which could affect national policies on the choice of antihypertensive drugs. It is predicted that future treatment of hypertension will be increasingly tailored to the epidemiologic profiles and medical costs of individual communities.