Thursday, December 13, 2012

Hypertension Treatment: Does Size Really Matter?

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7) was published in 2003.  Just to give you a bit of history, JNC-1 was published in 1976 with revisions coming out every 4 years up to JNC-5 in 1992.  It took 5 years to publish JNC-6 and when you do the math, 6 years went by before JNC-7 came out.  Well, it's been 9 years since JNC-7 and we're actually closing in on a decade since publication.  And in medicine, that's the equivalent of moving from dinosaurs to mammals.  I mention this because JNC-7 is the bible to which we all refer when making decisions on how to treat our patients w/hypertension (high blood pressure).  And one of the commandments is the use of thiazide diuretics as the preferred first-line agent in patients who have no other compelling condition such as diabetes, heart failure, etc.

But in a randomized double-blind trial published early online last week in Lancet, the authors concluded that body mass index (weight divided by height squared in the metric system) led to differences in response to antihypertensives.  More specifically, patients w/normal or overweight BMI did not respond to thiazide diuretics as well as those who were obese, while both responded similarly to calcium channel blockers.

In fact, the study included 1,616 participants with normal BMI, 4,157 who were overweight and 5,709 who were obese.  They were each given an ACE inhibitor (benazepril) and then randomized to either a thiazide diuretic (hydrochlorothiazide) or calcium channel blocker (amlodipine).  Thus this was really a study comparing hydrochlorothiazide to amlodipine since everyone received benazepril.  Depending upon BMI, avg age varied from 67yo to 71yo, essentially the young old if you will.  These patients were then followed just shy of 3 years on average.  The authors then assessed both cardiovascular death, non-fatal myocardial infarction, and/or stroke.

Bottom line: when it comes to clinical outcomes, not just blood pressure lowering, the combination of benazepril + amlodipine led to better results than benazepril + HCTZ in normal & overweight.  So if you must use benazepril + HCTZ, offer it to obese patients who fared better in terms of lower clinical outcome rates compared to normal weight patients.  It would appear that size dose matter!

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