Meta-analysis of the comparative effects of different classes of antihypertensive agents on brachial and central systolic blood pressure, and augmentation index.

AIMS: Brachial systolic blood pressure (bSBP) exceeds aortic pressure by a variable amount, and estimated central systolic blood pressure (cSBP) may be a better indicator of cardiovascular risk than bSBP. We undertook a systematic review and meta-analysis to compare the effect of single and multiple antihypertensive agents on bSBP, cSBP and augmentation index (AIx).
METHODS: A random effects meta-analysis was performed on 24 randomized controlled trials of antihypertensives with measurements of bSBP, cSBP and/or AIx. Separate analyses were performed for drug comparisons with or without placebo, and drug combinations.
RESULTS: In the placebo vs. drug meta-analysis, antihypertensive therapy reduced bSBP more than cSBP and there was no statistically significant evidence of heterogeneity by drug class, although the number of individual studies was small. In placebo-adjusted drug vs. drug comparison, treatment with β-blockers, omapatrilat and thiazide diuretics lowered cSBP significantly less than bSBP (i.e. central to brachial amplification decreased), whereas other monotherapies lowered cSBP and bSBP to similar extents. Sample sizes were too small and effect estimates insufficiently precise to allow firm conclusions to be made regarding comparisons between individual drug classes. Antihypertensive combinations that included β-blockers decreased central to brachial amplification. β-Blockers increased AIx, whereas all other antihypertensive agents reduced AIx to similar extents.
CONCLUSIONS: A reduction in central to brachial amplification by some classes of antihypertensive drug will result in lesser reductions in cSBP despite achievement of target bSBP. This effect could contribute to differences in outcomes in randomized clinical trials when β-blocker- and/or diuretic-based antihypertensive therapy are compared with other regimens.