Use of 24-Hour Ambulatory Blood Pressure Monitoring to Assess Antihypertensive Efficacy

Introduction: Goal rates, the percentage of patients with hypertension achieving recommended SBP/DBP, are a clinically important assessment of an antihypertensive agent’ efficacy. Twenty-four-hour ambulatory blood pressure monitoring (ABPM) allows accurate assessment of a patient’s hypertension and risk for cardiovascular events, and provides the most accurate measure of an antihypertensive agent’s efficacy throughout a 24-hour dosing interval.

Methods: A 12-week (4-week single-blind placebo run-in phase followed by an 8-week double-blind active treatment phase) randomized, parallel-group study reported that the recommended starting dose of the angiotensin II receptor antagonist (angiotensin receptor blocker; ARB) olmesartan medoxomil (Benicar™) 20 mg/day was more effective than starting doses of losartan potassium (Cozaar®) 50 mg/day, valsartan (Diovan®) 80 mg/day, or irbesartan (Avapro®) 150 mg/day in reducing cuff DBP in patients with essential hypertension. The present report includes analyses of secondary efficacy variables from this 12-week trial.

Results: The mean reduction in blood pressure from baseline to week 8 (end of treatment) was significantly greater with olmesartan medoxomil than with valsartan for all ABPM times analyzed (24 hours, daytime, night-time, and last 2 and 4 hours of monitoring). Statistical significance was reached for comparisons of oimesartan medoxomil with losartan potassium for a majority of times analyzed and with irbesartan for SBP in the last 4 hours of monitoring. Goal rates for accepted critical ambulatory blood pressure (ABP) values of < 130/80mm Hg for mean 24-hour ABP, <135/85mm Hg for mean daytime ABP, and <120/75mm Hg for mean night-time ABP were significantly greater for patients receiving olmesartan medoxomil than for those receiving losartan potassium or valsartan. Goal rates were numerically superior, but not statistically significant, to those achieved with irbesartan. Compared with losartan potassium or valsartan recipients, a significantly higher percentage of patients treated with olmesartan medoxomil achieved the 24-hour ABP goal of <130/85mm Hg. The last 2 and 4 hours of ABPM indicated that olmesartan medoxomil maintained larger mean decreases in blood pressure through the morning surge.

Discussion/Conclusion: ABP goal rates are a meaningful measure of antihypertensive efficacy. The effects on mean change from baseline in ABP and ABP goal rates after 8 weeks of treatment were numerically better, but not statistically significant, for olmesartan medoxomil than for irbesartan. However, olmesartan medoxomil was significantly more effective than losartan potassium or valsartan.