The OSCAR study was a multicenter prospective randomized study that examined the relative benefit of combined ARB (olmesartan 20 mg per day) plus calcium channel blocker (CCB) therapy vs. high-dose ARB monotherapy (olmesartan 40 mg per day) for prevention of cardiovascular events in elderly Japanese hypertensive patients. The present subanalysis of patients enrolled in the OSCAR study (n = 1078) was performed to assess whether baseline eGFR coupled with cardiovascular disease (CVD) could predict the relative benefit of these two treatments. Patients with baseline CVD (n = 769) and patients without baseline CVD (n = 309) were divided into two groups based on baseline eGFR; (i) patients with eGFR of < 60 ml min(-1) 1.73 m(-)(2) and (ii) those with eGFR of ⩾ 60 ml min(-1) 1.73 m(-2). There was a significant treatment-subgroup interaction among these four subgroups in relation to the incidence of primary outcome events(P = 0.007 for interaction). In patients with CVD and with eGFR of <60 ml min(-1) 1.73 m(-2), ARB plus CCB therapy was associated with a lower incidence of primary events than high-dose ARB therapy and the difference of the relative risk was statistically significant (hazard ratio: 3.525, 95% confidence interval (CI): 1.676-7.412, P < 0.001). The greater benefit of ARB plus CCB therapy vs. high-dose ARB therapy in this subgroup was associated with less visit-to-visit variability of systolic BP and diastolic BP. In conclusion, baseline eGFR coupled with baseline CVD seems to be a predictor of the relative efficacy of ARB plus CCB therapy vs. high-dose ARB therapy in the elderly hypertensive patients. ARB plus CCB therapy appears to be superior to high-dose ARB therapy for preventing cardiovascular events in the patients with CVD and with eGFR of <60 ml min(-1) 1.73 m(-2).
Trial registration: ClinicalTrials.gov NCT00134160.