Optimizing blood pressure control in the obese patient

Antihypertensive Effect of Irbesartan and Predictors of Response in Obesity-Associated Hypertension

BACKGROUND

Obesity-associated hypertension is difficult to treat and puts patients at a substantially increased risk of cardiovascular events. Irbesartan has previously been shown to effectively lower blood pressure (BP) in high-risk groups including patients with type 2 diabetes mellitus or nephropathy, and may therefore also be suitable for the treatment of obesity-associated hypertension. In this study we aimed to: (a) assess the efficacy and tolerability of irbesartan alone and in combination with hydrochlorothiazide in patients with obesity-associated mild-to-moderate hypertension; and (b) investigate patient-associated determinants of poor BP control in this patient group.

PATIENTS AND METHODS

This was a 3-month, prospective, open-label, multicentre, phase IV study in 72 479 hypertensive patients in 6989 general practices across Germany. Main outcome measures were BP reduction (primary parameter of effectiveness) and BP response rates after 3 months, as well as adverse events (AEs). Independent predictors of poor control were identified in a multivariate proportional odds model.

RESULTS

All of the patients were Caucasian, 50.5% were females, mean age was 62.1 +/- 11.1 years, mean bodyweight was 88.6 +/- 15.4kg, and mean body mass index (BMI) was 30.7 +/- 4.8 kg/m(2). Almost all the patients were overweight or obese (92.3%). From a baseline value of 162/94mm Hg, systolic and diastolic BP were reduced by a mean of -23/-12mm Hg after 3 months. 66.1% of the patients were responders (reduction of diastolic BP >/=10mm Hg), and 48.0% achieved BP normalisation (i.e. <140/90mm Hg). 79% of patients met their individual treatment goals as defined by the treating physician (mean 135/80mm Hg). AEs were reported in only 322 patients (0.4%). Factors requiring special attention in patients not achieving BP control were age (>55 years), high BMI category (>25 kg/m(2)), and increased waist circumference.

CONCLUSION

Treatment with irbesartan (+/- hydrochlorothiazide) appeared to be effective and well tolerated in the study population of patients with obesity- associated hypertension. Easily recognisable characteristics allow physicians to identify patients whose BP is likely to be difficult to control.

Is there a rationale for angiotensin blockade in the management of obesity hypertension?

Obesity, currently affecting >20% of the adult population in most Western countries, is a major risk factor for the development of hypertension. Hypertension in obese patients is, in the majority of instances, further complicated by the concomitant presence of dyslipidemia and insulin resistance. The latter is reflected by derangement of glucose homeostasis, ranging from hyperinsulinemia to frank type 2 diabetes. Hypertension in obese patients is also associated with an increased risk for left ventricular hypertrophy, endothelial dysfunction, renal hyperfiltration, microalbuminuria, and elevated markers of inflammation. Sodium retention, volume expansion, and increased cardiac output are common findings in obese individuals. These changes are largely attributable to increased activity of the sympathetic nervous system and insufficient suppression of the renin-angiotensin system. Recent data show increased expression of angiotensin II-forming enzymes in adipose tissue, and increased activity of the renin-angiotensin system has recently been implicated in the development of insulin resistance and type 2 diabetes. Accordingly, antihypertensive agents that block the renin-angiotensin system might be a beneficial strategy for treatment of obesity-related hypertension. Both angiotensin-converting enzyme inhibitors and angiotensin type-1 receptor blockers have been associated with favorable metabolic properties and end-organ protection in addition to their antihypertensive effects. Data from ongoing large trials will provide an indication of the protective and preventive effects of these treatment strategies while offering insights into the mechanisms linking obesity, hypertension, and other facets of the metabolic syndrome.