The study examines the relationship between systolic blood pressure and cardiovascular risk in adults with and without type 2 diabetes. Researchers did a meta-analysis of randomized controlled trials using the Blood Pressure Lowering Treatment Trialists’ Collaboration dataset. Eligible trials included those that reported at least 1000 person-years of follow-up in each group, compared blood pressure-lowering medications to placebo or other classes of blood pressure-lowering medications, or an intensive blood pressure-lowering strategy to a standard blood pressure-lowering strategy. They didn’t include trials on heart failure, acute myocardial infarction, or other acute situations. The primary outcome was the first occurrence of a fatal or non-fatal stroke or cerebrovascular disease, fatal or non-fatal ischaemic heart disease, or heart failure resulting in death or hospitalization. Investigators expressed the treatment effect as a reduction in this risk per 5 mm Hg in systolic blood pressure. Hazard ratios (HRs) were estimated using Cox proportional hazard models that were stratified by trial and by baseline systolic blood pressure categories (in 10 mm mm Hg increments from <120 mm Hg to ≥170 mm Hg). They utilized a Poisson regression model to assess absolute risk reductions across the follow-up period. Angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, β blockers, calcium channel blockers, and thiazide diuretics were all analyzed using a network meta-analysis framework to evaluate their respective effects on blood pressure. They analyzed information from 51 randomized clinical studies with a total of 358 533 individuals (58% men), of whom 103 325 (29%) had type 2 diabetes at baseline. These trials were published between 1981 and 2014. Both people with and without type 2 diabetes had similar blood pressure levels at the start: 149/84 mm Hg (SD 19/11) and 153/88 mm Hg (SD 21/12), respectively. Over 4.2 years median follow-up (IQR 3.0–5.0), a 5 mm Hg reduction in systolic blood pressure decreased the risk of major cardiovascular events in both groups, but with a weaker relative treatment effect in participants with type 2 diabetes (HR 0.94 [95% CI 0.91–0.98]) compared with those without type 2 diabetes (0.89 [0.87–0.92]; Pinteraction=0.0013). Higher absolute cardiovascular risk among type 2 diabetics meant the minimal difference in absolute risk reductions. Systolic blood pressure at baseline did not differ significantly across groups. Consistent with the primary results, stratified network meta-analysis showed no indication that relative treatment effects changed considerably between persons with type 2 diabetes and those without. Reducing blood pressure reduced major cardiovascular events in people with type 2 diabetes less than in those without diabetes. Both baseline blood pressure and drug class assignment did not affect relative risk reduction.
Source: thelancet.com/journals/landia/article/PIIS2213-8587(22)00172-3/fulltext
