Blood pressure control by drug group in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT)

Abstract

Blood pressure (BP) control rates and number of antihypertensive medications were compared (average follow-up, 4.9 years) by randomized groups: chlorthalidone, 12.5-25 mg/d (n=15,255), amlodipine 2.5-10 mg/d (n=9048), or lisinopril 10-40 mg/d (n=9054) in a randomized double-blind hypertension trial. Participants were hypertensives aged 55 or older with additional cardiovascular risk factor(s), recruited from 623 centers. Additional agents from other classes were added as needed to achieve BP control. BP was reduced from 145/83 mm Hg (27% control) to 134/76 mm Hg (chlorthalidone, 68% control), 135/75 mm Hg (amlodipine, 66% control), and 136/76 mm Hg (lisinopril, 61% control) by 5 years; the mean number of drugs prescribed was 1.9, 2.0, and 2.1, respectively. Only 28% (chlorthalidone), 24% (amlodipine), and 24% (lisinopril) were controlled on monotherapy. BP control was achieved in the majority of each randomized group-a greater proportion with chlorthalidone. Over time, providers and patients should expect multidrug therapy to achieve BP <140/90 mm Hg in a majority of patients.

Figure 1

Characteristics that predicted better or worse blood pressure control (BP<140/90 mmHg) within each drug group. Depicted are odds ratios (OR) and their 95% confidence intervals (CI) from three multiple logistic regression analyses of BP control at year-3; separate analyses were done for each randomized treatment group. An odds ratio >1.0 indicates the corresponding characteristic is associated with better BP control than its complementary subgroup (e.g., the odds ratio of 1.2 for lisinopril men indicates 20% better BP control than among lisinopril women); an odds ratio <1.0 indicates worse BP control for the corresponding subgroup relative to its complement. The sample sizes for the respective logistic models were 11,262 (chlorthalidone), 6,697 (amlodipine), and 6,423 (lisinopril). † In a model combining all three treatment groups and including drug main effects and interaction terms (A/C and L/C), the relative odds of BP control differed significantly by treatment group only for race (A/C interaction OR=0.911, p<0.01, and L/C interaction OR=0.895, p<0.001).