In Elderly Hypertensive Patients, Combination ARB and Calcium Channel Blocker Produces Similar Outcomes to High-Dose ARB Alone

NEW ORLEANS, LA--Elderly patients with hypertension have similar rates of cardiovascular events and death when treated with a combination of an angiotensin II receptor blocker (ARB) and a calcium channel blocker (CCB) compared to high-dose ARB alone, according to the results of a subanalysis of the OSCAR study that were presented at ACC.11, the American College of Cardiology's 60th Annual Scientific Session.

“The OSCAR study provides the first evidence showing that a standard dose of an ARB plus CCB combination is superior to high-dose ARB treatment in reducing adverse events in elderly hypertensive patients with cardiovascular disease,” said lead study author Hisao Ogawa, MD, PhD, of Kumamoto University, Japan. These results contribute to an understanding of optimal treatments for this patient population, for whom CCBs are generally recommended as first-line treatment.

In the OSCAR study, 1,164 high-risk elderly outpatients aged 65-84 years with hypertension were enrolled at 134 centers throughout Japan from June 2005 to May 2007. Included were those unable to manage their high blood pressure through standard-dose monotherapy with the ARB olmesartan (eg, SBP ≥140 mmHg and/or DBP ≥90 mmHg) and at least one CV disease risk factor, defined as cerebrovascular disease, cardiac disease, vascular disease, renal dysfunction, or type 2 diabetes.

After a run-in treatment period of olmesartan 20mgPatients were randomized to receive high-dose olmesartan 40mg/day (n=578) or a CCB (azelnidipine or amlodipine) combined with olmesartan at 20mg/day (n=586). Primary study end point was a composite of fatal and nonfatal CV events that included cerebrovascular disease, coronary artery disease, heart failure, other atherosclerotic disease, diabetic complications, and deterioration of renal function as well as noncardiovascular (all-cause) death.

Mean age at baseline was 73.6 years in both treatment groups; 43.9% of the patients in the high-dose ARB group were male, as were 44.5% in the combination therapy group. Approximately 70% of those in both groups had a history of cardiovascular disease, including stroke, myocardial infarction, and heart failure. More than 50% of patients in each group had type 2 diabetes mellitus.

At 36-month follow-up, blood pressure was found to be adequately controlled in both treatment groups; however, in those receiving combination therapy, blood pressure was reduced to significantly lower levels than monotherapy (mean SBP and DBP were lower by 2.4 mmHg [P=0.0315] and 1.7mmHg [P=0.0240], respectively). No significant difference was observed between the two cohorts in the number of primary end points; 58 events occurred in the monotherapy group and 48 occurred in the combination group (HR 1.31 [0.89–1.92]; P=0.1717).

A statistically significant difference was observed in a subgroup analysis of patients with preexisting CV disease. In this analysis, those randomized to the combination therapy group had significantly fewer occurrences of CV events and death (n=34) than those in the monotherapy group (n=51) (HR 1.63 [1.06–2.52] P=0.0261).

Conversely, another subgroup analysis that included only patients with diabetes showed a higher incidence of the primary end point in the combination therapy group, 14 events vs. 7 in the monotherapy group, although this difference was not statistically significant (HR 0.52 [0.21–1.28] P=0.1445). The interaction for the primary endpoint between these two groups (preexisting CV disease and diabetes) was P=0.0241.

Dr. Ogawa noted these data suggest relative effect of the combination depends on the presence of CV disease or diabetes and these risk factors should be considered before prescribing high-dose ARBs.