Contributions of Systolic and Diastolic Blood Pressures to Cardiovascular Outcomes in the ALLHAT Study

BACKGROUND SBP and DBP have important associations with cardiovascular events, but are seldom considered simultaneously. OBJECTIVES This study sought to simultaneously analyze systolic blood pressure (SBP) and diastolic blood pressure (DBP) measurements on the associated risk of a primary composite outcome of all-cause mortality, myocardial infarction (MI), congestive heart failure (CHF), or stroke. METHODS This study analyzed ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial) data, which randomized adults to chlorthalidone, amlodipine, or lisinopril. The authors evaluated the simultaneous association of repeated SBP and DBP measurements on the primary composite outcome, and each outcome using proportional hazards regression. The authors report hazard ratios using a "heat map" to represent high and low risk according to SBP and DBP combinations. RESULTS During a median follow-up of 4.4 years (interquartile range: 3.6-5.4 years), 33,357 participants experienced 2,636 MIs, 866 CHF events, 936 strokes, and 3,700 deaths; 8,138 patients (24.4%) had at least 1 event. For the composite outcome, all-cause mortality, MI, and CHF, a U-shaped association was observed with SBP and DBP, but the SBP and DBP associated with the lowest hazards differed for each outcome. For example, SBP/DBP of 140-155/70-80 mm Hg was associated with the lowest HR for all-cause mortality, compared with 110-120/85-90 mm Hg for MI and 125-135/70-75 mm Hg for CHF. In contrast, the association of SBP and stroke was linear. CONCLUSIONS The risk pattern of SBP and DBP differs by clinical outcomes, and the SBP and DBP associated with the lowest risk. Our results suggest individualization of blood pressure targets may depend in part on the cardiovascular event for which the patient is most at risk.