PharmacotherapyOriginal researchRetrospective Analysis of Real-World Efficacy of Angiotensin Receptor Blockers Versus Other Classes of Antihypertensive Agents in Blood Pressure Management
Introduction
Hypertension is a major modifiable risk factor for cardiovascular (CV) disease1, 2 and the most common risk factor for death, both worldwide3 and in Canada.4, 5 Numerous randomized controlled clinical trials have demonstrated that effective blood pressure (BP) control using any of the 5 conventional antihypertensive drug classes is associated with significant reductions in CV risk in people with hypertension.6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 Based largely on results from these and similar studies, hypertension treatment guidelines recommend lowering BP to <140/90 mm Hg in the general population and to <130/80 mm Hg in patients with diabetes and renal disease.4, 20, 21, 22, 23 According to these guidelines, the initial choice of antihypertensive treatment strategy depends largely on patients' comorbidities and degree of hypertension. For example, people with diabetes, chronic kidney disease, and/or BP ≥20 mm Hg above the systolic BP (SBP) goal or ≥10 mm Hg above the diastolic BP (DBP) goal should be initiated on ≥2 agents; those with CKD should receive at least 1 angiotensin-converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) and most combination therapies should include a thiazide diuretic according to standard of care.4
Treatment guidelines are continuously updated to reflect the ever-increasing volume of data from clinical studies and published meta-analyses. However, clinical trial populations often do not represent those seen in real-life clinical practice.21, 24, 25, 26, 27 Factors such as persistence with treatment tend to be artificially high in clinical trials. In the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), for example, persistence with any antihypertensive agent was 96% at 1 year compared with 5% to 75% in observational studies.28, 29, 30, 31 Such differences may lead to over-exaggerated treatment efficacy in responsive patients who may not have persisted with treatment in a real-world setting or to under-exaggerated efficacy in unresponsive patients who may have switched to a more suitable drug in clinical practice.21 It is therefore important that guidelines should take into account results from observational real-world studies as well as those from clinical trials.29, 30, 31, 32
Like randomized clinical trials, observational studies are often designed to assess treatment efficacy and tolerability in specific patient populations, such as those with hypertension and diabetes or kidney disease.33, 34, 35, 36, 37, 38, 39 Few studies have captured treatment efficacy in the broad range of patients that are routinely seen in clinical practice. Recently, the observational The Health Improvement Network (THIN) study examined the BP-lowering efficacy of various antihypertensive drug classes in primary care in the United Kingdom.40, 41, 42 In this study, patients prescribed ARBs, either as monotherapy or as part of a combination therapy regimen, were more likely to achieve and maintain target BP than patients using other classes of antihypertensive agents.40, 41, 42 The aim of our study was to compare the BP-lowering efficacy and long-term persistence rates of ARB- versus non–ARB-based monotherapy, dual, and tri-therapies in a “real world” primary care population in Canada. The CV event rates associated with each treatment strategy were also assessed.
Section snippets
Data Source
This retrospective observational study utilized data collected from routine primary care practices in Canada, stored in the South Western Ontario (SWO) database. The longitudinal investigation was carried out in a geographically defined area comprising rural and urban clinical practices in London, Ontario, Canada, and surrounding counties with a catchment of 1.5 million inhabitants. This retrospective study began in 2000 and, at the time of this report in 2010, included information from 53
Blood Pressure Control With Monotherapy
Overall, 10,120 adult, nondiabetic patients with hypertension were initiated on monotherapy treatment in 2005 and continued with their prescribed treatment for at least 9 months. Over 90% of the patients were white. The mean age of the target population was 65 years; mean weight 81.3 kg; 41% were male; and mean BP at index date was 149/84 mm Hg (Table I). There were no significant differences across antihypertensive drug classes for age, sex, or baseline BP. After 9 months of treatment with
Discussion
In primary care practice in Canada, ARB, ACEI, and CCB monotherapies were significantly more effective than β-blockers and diuretics for the attainment of a BP target <140/90 mm Hg in nondiabetic patients with mild to moderate hypertension.45 Although the proportion of people reporting target BP was slightly higher with ARB monotherapy than with ACEI or CCB monotherapy, the between-group differences were not statistically significant. In a similar study, records of 158,995 adults with
Conclusions
In a 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.
Acknowledgments
Both authors were sole contributors to the collection and interpretation of the data, the intellectual development, writing of the manuscript, extensive editing, and final approval of this article. The authors received no financial support or other compensation related to its development. This report was supported by an unrestricted grant from Bristol-Myers Squibb/Sanofi-Synthelabo. The authors do not have any conflict of interest with the sponsors of this report. The authors thank PPSI, a
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