Systolic blood pressure and mortality after stroke: too low, no go?

BACKGROUND AND PURPOSE: Recent studies suggest a J-shaped association between systolic blood pressure (SBP) and cardiovascular events. The optimal SBP target after stroke remains unknown. We assessed the link between SBP and mortality after stroke.

METHODS

We included adults (≥20 years) with self-reported stroke who participated in the National Health and Nutrition Examination Surveys 1998 to 2004, with mortality assessment in 2006. Baseline SBP was categorized as low to normal (<120 mm Hg), normal (120-140 mm Hg), and high (≥140 mm Hg). Independent relationships between baseline SBP and all-cause and vascular mortality were assessed using Cox proportional hazards.

RESULTS

Of 31 126 adult participants, 455 had self-reported stroke and baseline BP readings: 19% had low to normal, 31% had normal, and 50% had high SBP. Two years after assessment, the low to normal SBP group tended to have the highest cumulative all-cause mortality (11.5%), compared with mortality rates of 8.5% and 7.5% in the normal and high SBP groups, respectively. Similar patterns were seen with vascular mortality. After adjusting for covariates, compared with the high SBP group, the low to normal group had higher all-cause mortality (adjusted hazard ratio, 1.96; 95% confidence interval, 1.13-3.39; P=0.017) and trended toward higher vascular mortality (adjusted hazard ratio, 2.08; 95% confidence interval, 0.93-4.68; P=0.075). Compared with the normal BP group, the risk of all-cause and vascular mortality trended higher in low to normal BP group but did not achieve statistical significance.

CONCLUSIONS

After stroke, compared with SBP in the high range, low to normal SBP is associated with poorer mortality outcomes.