Optimal achieved blood pressure in acute intracerebral hemorrhage: INTERACT2

Abstract

Objectives: To investigate the effects of intensive blood pressure (BP) lowering according to baseline BP levels and optimal achieved BP levels in patients with acute intracerebral hemorrhage (ICH).

Methods: INTERACT2 was an open, blinded endpoint, randomized controlled trial in 2,839 patients with ICH within 6 hours of onset and elevated systolic BP (SBP) (150-220 mm Hg) who were allocated to receive intensive (target SBP <140 mm Hg within 1 hour, with lower limit of 130 mm Hg for treatment cessation) or guideline-recommended (target SBP <180 mm Hg) BP-lowering treatment. Outcome was physical function across all 7 levels of the modified Rankin Scale at 90 days.

Results: Analysis of the randomized comparisons showed that intensive BP lowering produced comparable benefits on physical function at 90 days in 5 subgroups defined by baseline SBP of <160, 160-169, 170-179, 180-189, and ≥190 mm Hg (p homogeneity = 0.790). Analyses of achieved BP showed linear increases in the risk of physical dysfunction for achieved SBP above 130 mm Hg for both hyperacute (1-24 hours) and acute (2-7 days) phases while modest increases were also observed for achieved SBP below 130 mm Hg.

Conclusions: Intensive BP lowering appears beneficial across a wide range of baseline SBP levels, and target SBP level of 130-139 mm Hg is likely to provide maximum benefit in acute ICH.

Classification of evidence: This study provides Class I evidence that the effect of intensive BP lowering on physical function is not influenced by baseline BP.

Figure 1. Effects of randomized intensive blood pressure–lowering treatment on modified Rankin Scale scores at 90 days by baseline SBP risk reductions were estimated using ordinal analyses

The p value for homogeneity, which tested the consistency of the treatment effects among subgroups, was 0.790. Solid boxes represent estimates of treatment effect on the risk of outcomes. Centers of the boxes are placed at the estimates of the effect; areas of the boxes are proportional to the reciprocal of the variance of the estimates. Horizontal lines represent 95% CIs. Diamonds represent estimates and 95% CI for overall effects in total subjects. CI = confidence interval; SBP = systolic blood pressure.

Figure 2. Effects of achieved SBP on modified Rankin Scale score at 90 days

(A) 1–24 hours; (B) 2–7 days. Odds ratios and 95% CIs (shaded areas) were estimated using ordinal analyses and were shown according to achieved SBP after adjustment for age, sex, region, time from onset to randomization, NIH Stroke Scale score, volume and location of hematoma, intraventricular extension, and randomized treatment. The reference was achieved SBP of 130 mm Hg. CI = confidence interval; SBP = systolic blood pressure.