Blood pressure lowering efficacy of antihypertensive drugs and their combinations: a systematic review and meta-analysis of 500 randomised, double-blind placebo-controlled trials

Abstract Background Each 1 mmHg reduction in systolic blood pressure (SBP) reduces the risk of major cardiovascular disease events by about 2%. However, there are currently no tools to provide randomised trial-derived estimates of blood pressure (BP)-lowering efficacy of different antihypertensive regimens despite the vast number of possible drug-dose permutations. There has also been no attempt to classify efficacy of treatment regimens into low, moderate, and high intensity. Purpose We aimed to quantify the BP-lowering efficacy of the five major classes of antihypertensive drugs and their combinations. Methods We conducted a systematic review and meta-analysis of randomised double-blind placebo-controlled trials. CENTRAL, MEDLINE and Epistimonikos were searched from inception until December 2022 to identify trials, that compared angiotensin-converting-enzyme inhibitors, angiotensin II receptor blockers, beta-blockers, calcium channel blockers, and diuretics versus placebo, for 4-26 weeks. Primary outcomes were reduction in SBP and diastolic blood pressure (DBP). Doses were classified into standard dose based on the World Health Organisation Defined Daily Dose. BP-lowering efficacy was estimated for each drug and dose using fixed-effects meta-analyses and meta-regressions, standardised to baseline SBP 154 mmHg. Treatment regimens were categorised into low, moderate, and high intensity according to estimated SBP-lowering efficacy of <10, 10-19 and ≥20 mmHg, respectively. Results A total of 500 trials (106,358 participants, 44% female) were included, which included 66 single antihypertensive drugs (monotherapy) and 89 two drug (dual) combinations. The mean baseline BP was 154/100 mmHg and mean follow-up was 8.6 weeks. Monotherapy at one standard dose reduced SBP by 8.5 (95% CI, 8.2-8.9) mmHg, with an additional 1.2 (1.0-1.5) mmHg reduction for each 10 mmHg higher pre-treatment SBP, and an additional 1.5 (1.2-1.8) mmHg reduction with each doubling in dose. There was significant heterogeneity between monotherapies, and 72% were classified as low intensity efficacy. Dual combinations at one standard doses of both the drugs reduced SBP by 15.2 (13.4-17.1) mmHg, and an additional 2.6 (1.4-3.8) mmHg reduction with doubling the doses of both the drugs. There was considerable heterogeneity between dual combinations and 59% were classified as moderate, and 11% as high intensity efficacy. The BP lowering efficacy of adding additional drug classes was confirmed to be additive after accounting for pre-treatment SBP. Triple combinations were classified as high intensity efficacy based on meta-regression analyses. Conclusions There is significant variability in the efficacy of different BP-lowering regimens. The present analyses, available in an online tool, can estimate the BP lowering efficacy for any combination of drug(s) and dose(s), and can classify treatment regimens into low, moderate or high intensity.