Heart failure in ALLHAT: did blood pressure medication at study entry influence outcome?

Author(s): Grimm RH, Davis BR, Piller LB, Cutler JA, Margolis KL, Barzilay J, Dart RA, Graumlich JF, Murden RA, Randall OS, ALLHAT Collaborative Research Group

Affiliation(s): Department of Internal Medicine, University of Minnesota Medical School, Minneapolis, MN, USA.

Publication date & source: 2009-09, J Clin Hypertens (Greenwich)., 11(9):466-74.

Publication type: Randomized Controlled Trial; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

J Clin Hypertens (Greenwich). 2009;11:466-474. (c)2009 Wiley Periodicals, Inc.Lower heart failure (HF) rates in individuals taking chlorthalidone vs amlodipine, lisinopril, or doxazosin were unanticipated in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). HF differences appeared early, leading to questions about the possible influence of pre-enrollment antihypertensive drugs. A post hoc study evaluated hospitalized HF events. During year 1479 individuals had HF, with pre-entry antihypertensive medication data obtained on 301 patients (63%). Case-only analysis examined interactive effects (interaction odds ratio [OR, ratio of ORs]) of previous medication and ALLHAT treatment on HF outcomes, eg, did treatment effect differ by pre-entry antihypertensive class? Among cases, 39%, 37%, 17%, and 47% were taking pre-entry diuretics, angiotensin-converting enzyme inhibitors, beta-blockers, and calcium channel blockers, respectively. Interaction OR for year 1 HF for amlodipine vs chlorthalidone for patients taking vs not taking diuretics pre-entry was 1.08 (95% confidence interval [CI], 0.53-2.21; P=.83); for lisinopril vs chlorthalidone, 1.33 (95% CI, 0.65-2.74; P=.44); and for doxazosin vs chlorthalidone, 1.13 (95% CI, 0.57-2.25; P=.73). Controlling for other pre-entry antihypertensives yielded similar results. There was no significant evidence that pre-entry drug type explained observed hospitalized HF differences by ALLHAT treatment.