Effect Heterogeneity in Intensive BP Control

A secondary analysis of data from a US randomized clinical trial suggests that smokers with high blood pressure (BP) may have a higher rate of cardiovascular events associated with intensive BP control. Of 9361 participants in the trial, 466 were current smokers with systolic BP > 144 mm Hg at baseline, with 230 randomized to the training data set to identify potential heterogeneous treatment effects by a random forest–based analysis, and 236 to the testing data set to test potential heterogeneous treatment effects. 286 participants were male, and the mean age was 60.7 years. Combinations of 2 covariates (i.e., baseline smoking status and systolic BP) distinguished participants who were differentially affected by the intervention. In the testing data, Cox proportional hazards models for the primary outcome (myocardial infarction, other acute coronary syndromes, stroke, heart failure, or death from cardiovascular causes) revealed a number needed to harm of 43.7 to cause 1 event across 3.3 years among current smokers with systolic BP > 144 mm Hg (hazard ratio, 10.6) for target of < 120 mm Hg vs < 140 mm Hg, despite overall benefit from intensive BP control. This subgroup was also associated with a higher likelihood to experience acute kidney injury under intensive BP control (hazard ratio, 9.4), and a significant and sustained reduction in diastolic BP. The findings are consistent with other studies and provide additional, suggestive evidence that diastolic BP regulation may play an important role in reducing the risk of serious adverse events, especially in smokers and the elderly who may be more vulnerable to a significant reduction in perfusion pressure.  Source: https://jamanetwork.com/