Correlation between day-by-day blood pressure variability and outcome after acute ischemic stroke

Abstract

Objective To investigate correlation between the day-by-day blood pressure variability within 1 week and the outcomes at 6 months after acute ischemic stroke. Methods From January 2013 to December 2015, the patients with acute ischemic stroke admitted to hospital were registrated consecutively. Blood pressure was monitored every morning within 7 d after admission and the parameters of blood pressure variability were calculated. They were followed up for 6 months. The outcomes were evaluated according to the modified Rankin scale (mRS). Good outcome was defined as the mRS score 0 to 2. The clinical characteristics, blood pressure and day-by-day blood pressure variability parameters were compared between the good outcome group and the poor outcome group. Multivariable logistic regression analysis was used to determine the correlation between the day-by-day blood pressure variability and the outcomes at 6 months. Results A total of 169 patients were enrolled in the study, including 89 (52.7%) with poor outcomes. The day-by-day mean systolic blood pressure (147.1±15.9 mmHg vs. 139.6±19.0 mmHg; t=2.666, P=0.008; 1 mmHg=0.133 kPa), standard deviation of systolic blood pressure (median and interquartile range: 16.5 [13.7-19.4] mmHg vs. 13.4 [10.7-18.3] mmHg; Z=2.909, P=0.004), and maximum-minimum difference of systolic blood pressure (47.0 [38.0-56.0] mmHg vs. 37.0 [29.0-49.0] mmHg; Z=3.634, P<0.001) of the poor outcome group were significantly higher than those of the good outcome group. Multivariate logistic regression analysis showed that the daily increased maximum-minimum difference of systolic blood pressure was an independent risk factor for poor outcome at 6 month after onset (odds ratio, 1.028, 95%confidence interval 1.007-1.050; P=0.008). Conclusions Increased day-by-day blood pressure variability was independently associated with the poor outcome after acute ischemic stroke. Key words: Stroke; Brain Ischemia; Blood Pressure; Prognosis; Time Factors