Pharmacoeconomical Evaluation of Combination Therapy for Lifetime Hypertension Treatment in Japan

Background As the observation periods of large-scale clinical studies are relatively short, the pharmacoeconomical advantage of different first-line drugs in lifetime hypertension treatment is unknown. Methods Based on the results of large-scale clinical studies, phase III clinical trials and epidemiological data, we constructed a Markov model for patients with moderate essential hypertension to study the cost-effectiveness of lifetime hypertension treatment. In 55-year-old patients with moderate hypertension in the absence and presence of concomitant diabetes, four treatment regimens were compared: initial angiotensin II receptor blocker (ARB) with additional calcium antagonist if ARB therapy was insufficient (A C group); initial calcium antagonist with additional ARB (C A group); initial ARB with additional diuretic (A D group); and initial diuretic with additional ARB (D A group). It was assumed that approximately 20% of patients received combination therapies and there was no difference in the treated blood pressure. Olmesartan medoxomil, azelnidipine and trichlormethiazide were the ARB, calcium antagonist and diuretic used, respectively. Results Among patients without diabetes, expected survival and costs were similar in all treatment groups. Among patients with concomitant diabetes, expected survival was longest and expected costs were lowest in the A C group. Expected survival decreased and expected costs increased in the order of A D group, C A group, and D A group. The presence of concomitant diabetes affected cost-effectiveness. Conclusion Our study suggests no pharmacoeconomical advantage among any of the treatment regimens in those patients without diabetes. In contrast, treatment with ARB with additional calcium antagonist may be a superior lifetime hypertensive treatment regimen for hypertensive patients with diabetes.