Systolic blood pressure trajectory and cardiovascular outcomes: An analysis using data in the Systolic Blood Pressure Intervention Trial

Background Blood pressure changes in response to medication intensification differ over time across individuals, and could affect their cardiovascular outcomes. We aimed to investigate the relationship between systolic blood pressure (SBP) trajectory and cardiovascular outcomes using data from the Systolic Blood Pressure Intervention Trial (SPRINT). Methods Groups of SBP trajectory were modelled separately in the standard and intensive treatment groups. SBP at each site visit post randomisation were used for modelling by group-based trajectory with latent class growth model. We classified six SBP trajectories (on target [reference group], near target, and off target in the intensive treatment group; on target-below 130, on target-below 140, and off target in the standard treatment group). A Cox-proportional hazard model was used to analyse the effects of SBP trajectory on the primary composite outcome, death from any cause, and the composite of the primary outcome or death from any cause. Results The respective mean SBP was 119 +/- 5, 128 +/- 6, 141 +/- 8, 124 +/- 4, 136 +/- 4, and 147 +/- 6 mm Hg. With respect to the primary composite outcomes, the standard-on target (below 130) had the highest risk (adjusted hazard ratio [lower to upper confidence interval], 2.525 [1.865-3.420]), despite its mean SBP was the second lowest of the six groups. The standard-on target (below 140) had a higher risk (1.323 [1.056-1.657]) when compared with the intensive-on target. However, the standard-on target (below 140) had a similar risk (1.12 [0.861-1.458]) when compared with the intensive-near target, despite an 8 mm Hg difference in mean SBP (136 vs 128 mm Hg, P < .001). Conclusion An SBP treatment target of <120 mm Hg was only associated with a better cardiovascular outcome compared with a treatment target of <140 mm Hg, provided that the target of <120 mm Hg was reached. Trial registration: ClinicalTrials.gov NCT01206062. Registered 21 September 2010.