Background: Efficacy of blood pressure (BP) lowering may differ between clinical trials and what is observed in clinical practice. These differences may contribute to poor BP control rates among those at risk.
Objective: We conducted an observational study to determine the BP-lowering efficacy of angiotensin receptor blocker (ARB) versus non-ARB-based antihypertensive treatments in a large Canadian primary care database.
Methods: We analyzed the South Western Ontario database of 170,000 adults (aged >18 years) with hypertension persisting with antihypertensive medication for ≥9 months. Routine standard of care office BP was measured using approved manual aneroid or automated devices. BP <140 mm Hg and/or <90 mm Hg ≤9 months after treatment initiation, persistence (presence of initial antihypertensive prescription at the first, second, third, and fourth year anniversary) with antihypertensive therapy, and the presence of a cardiovascular (CV) event (ie, myocardial infarction) were studied.
Results: After 9 months of monotherapy, 28% (978 of 3490) of patients on ARBs achieved target BP versus 27% (839 of 3110) on angiotensin-converting enzyme inhibitors (ACEIs) (P > 0.05), 26% (265 of 1020) on calcium channel blockers (CCBs) (P > 0.05), 21% (221 of 1050) on β-blockers (P = 0.002), and 19% (276 of 1450) on diuretics (P = 0.001). Attainment rates were significantly higher with irbesartan (38%; 332 of 873) versus losartan (32%; 335 of 1047; P = 0.01), valsartan (19%; 186 of 977; P = 0.001), and candesartan (25%; 148 of 593; P = 0.001). BP goal attainment rates were significantly higher when ARB was compared with non-ARB-based dual therapy (39%; 1007 of 2584 vs 31%; 1109 of 3576; P = 0.004); irbesartan + hydrochlorothiazide (HCTZ) was significantly higher than losartan + HCTZ (36%; 500 of 1390 vs 20%; 252 of 1261; P = 0.001). For patients receiving dual or tri-therapy, 48% (667 of 1390) of patients receiving irbesartan reached target BP versus 41% to 42% for losartan (517 of 1261), valsartan (194 of 462), and candesartan (168 of 401) (P = 0.001 for each). After 4 years, persistence rates were not statistically different among ARB, CCB, and diuretic monotherapies, but appeared somewhat higher with ACEIs and β-blockers (78%, 78%, 79%, 91%, and 84%, respectively). Persistence was not significantly different between irbesartan and losartan monotherapy (76% for both; P > 0.05), but was significantly higher with irbesartan + HCTZ versus losartan + HCTZ (96% vs 73%, respectively; P = 0.001). Patients treated with ARBs reported fewer CV events than those receiving ACEIs or CCBs (4.3% vs 7.0% and 11.0%, respectively; P < 0.001). Within the ARB class, the lowest rate was with irbesartan (3.0% vs 4.6%-5.0% for other ARBs; P < 0.02).
Conclusions: In this real-world setting, hypertensive adults treated with ARBs versus β-blockers or diuretics were more likely to have evidence-based target BP recorded. In addition, patients using ARBs versus ACEIs or CCBs had fewer reports of CV events.
Copyright © 2011 Elsevier HS Journals, Inc. All rights reserved.