Background:
The Systolic Blood Pressure Intervention Trial enrolled patients aged 50 or older with at least one cardiovascular disease risk factor, but free of prior symptomatic stroke. Patients were assigned to two blood pressure reduction goals (<140 versus 120 mm Hg). There was not a significant difference in the rate of stroke, making this an ideal cohort to refine risk prediction of primary stroke, which is understudied in patients with adequate blood pressure control and a rigorously adjudicated outcome of stroke.
Methods:
The primary outcome is ischemic stroke. We fit Cox models to the primary outcome and evaluated all baseline demographic variables to determine which would be most predictive of stroke, which we then used to create a prediction score.
Results:
We included 9,361 patients with a mean (SD) age of 67.9 (9.4) years and 171 (1.8%) patients met the primary outcome of stroke. For our prediction model, we gave one point each for history of TIA, atrial fibrillation, congestive heart failure, or diabetes. Patients with 2 or more points were collapsed, making three possible scores of 0, 1, and 2, which had rates of stroke of 1.5% (117/8042), 3.2% (30/933), and 6.2% (24/386) (p<0.001). Compared to a score of 0, the hazard ratios for stroke of score 1 and 2 were 2.3 (95% CI, 1.6-3.5) and 4.6 (95% CI, 2.9-7.1) (both p<0.001) (Figure 1).
Conclusion:
A simple scoring system can improve prediction of ischemic stroke from 1.8% to 6.2% in patients with no prior history of stroke and excellent blood pressure control. This information could be used to improve patient selection for clinical trials or for identifying patients for more aggressive primary prevention strategies.
Prevalence of Inadequate Blood Pressure Control Among Veterans After Acute Ischemic Stroke Hospitalization