BMI and the cardiovascular protective effect of diuretics
posted at 19/12/2012 2:05 PM GMT on bmj.com
Effects of body size and hypertension treatments on cardiovascular event rates: subanalysis of the ACCOMPLISH randomised controlled trial
The Lancet, Early Online Publication, 6 December 2012
doi:10.1016/S0140-6736(12)61343-9Cite or Link Using DOI
In previous clinical trials in high-risk hypertensive patients, paradoxically higher cardiovascular event rates have been reported in patients of normal weight compared with obese individuals. As a prespecified analysis of the Avoiding Cardiovascular Events through Combination Therapy in Patients Living with Systolic Hypertension (ACCOMPLISH) trial, we aimed to investigate whether the type of hypertension treatment affects patients’ cardiovascular outcomes according to their body size.
On the basis of body-mass index (BMI), we divided the full ACCOMPLISH cohort into obese (BMI ≥30, n=5709), overweight (≥25 to <30, n=4157), or normal weight (<25, n=1616) categories. The ACCOMPLISH cohort had already been randomised to treatment with single-pill combinations of either benazepril and hydrochlorothiazide or benazepril and amlodipine. We compared event rates (adjusted for age, sex, diabetes, previous cardiovascular events, stroke, or chronic kidney disease) for the primary endpoint of cardiovascular death or non-fatal myocardial infarction or stroke. The analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00170950.
In patients allocated benazepril and hydrochlorothiazide, the primary endpoint (per 1000 patient-years) was 30·7 in normal weight, 21·9 in overweight, and 18·2 in obese patients (overall p=0·0034). However, in those allocated benazepril and amlodipine, the primary endpoint did not differ between the three BMI groups (18·2, 16·9, and 16·5, respectively; overall p=0·9721). In obese individuals, primary event rates were similar with both benazepril and hydrochlorothiazide and benazepril and amlodipine, but rates were significantly lower with benazepril and amlodipine in overweight patients (hazard ratio 0·76, 95% CI 0·59—0·94; p=0·0369) and those of normal weight (0·57, 0·39—0·84; p=0·0037).
Hypertension in normal weight and obese patients might be mediated by different mechanisms. Thiazide-based treatment gives less cardiovascular protection in normal weight than obese patients, but amlodipine-based therapy is equally effective across BMI subgroups and thus offers superior cardiovascular protection in non-obese hypertension.
COMMENT: This article may explain the paradoxical observation in some clinical trials than normal weight subjects has poorer outcomes than obese subjects. It appears the diuretic therapy is more effective in obese subjects than in normal weight subjects. It seems to me convincing and suggests that we should reconsider the use of diuretics in normal weight persons. In the interest of full disclosure, the study was funded by Norvartis who markets benazepril.