Research in context
Evidence before this study
Although the benefits of blood pressure lowering treatment for prevention of cardiovascular disease are well established, the extent to which these effects differ by baseline blood pressure, presence of comorbidities, or drug class is less clear.
Added value of this study
Our study provides a comprehensive systematic review and meta-analysis of all available large-scale blood pressure lowering randomised trials. Our findings show that pharmacological blood pressure lowering results in similar proportional reductions in risk of cardiovascular disease and death to a mean baseline systolic blood pressure of less than 130 mm Hg. Furthermore, we noted that proportional risk reductions are broadly similar among individuals with or without major cardiovascular comorbidities. Finally, our findings emphasise the fact that, despite the general efficacy of commonly prescribed blood pressure lowering drug classes in preventing cardiovascular disease, there are some significant differences among them in the reduction of risk of specific clinical outcomes. For example, calcium channel blockers seem to be more effective than other classes of drugs for stroke prevention, and diuretics are more effective for prevention of heart failure.
Implications of all the available evidence
Our study has several implications for clinical practice. First, our findings suggest that blood pressure lowering to levels below those recommended in current guidelines (ie, systolic blood pressure of less than 140 mm Hg) will reduce the risk of cardiovascular disease. Second, by showing no evidence for a threshold below which blood pressure lowering ceases to work, the findings call for blood pressure lowering based on an individual's potential net benefit from treatment rather than treatment of the risk factor to a specific target. Third, the broad consistency of the findings across patients with or without prior vascular disease could help to simplify clinical guidelines for use of blood pressure lowering drugs. Fourth, the differences we identified between classes of drugs support more targeted drug use for individuals at high risk of specific outcomes (eg, calcium channel blocker therapy for individuals at high risk of stroke).