Objective To assess the J shaped curve between the value of blood pressure and the occurrence of
stroke in the antihypertension treatment.
Methods A retrospective analysis was conducted in the 2059 patients accepted antihypertension
treatment in outpatients or hospitalized from January 2009 to October 2013. The restricted
cubic spline (RCS) fitting Cox regression model was used to evaluate the relationship between
different blood pressure cut-off value and stroke. The Kaplan-Meier methods was used to assess
the incidence of stroke during follow-up, and Cox proportion risk model was used to analyze the
independent risk factors for stroke.
Results The 1, 3, 5 year cumulative stroke incidence rates in the whole patients were 2.5%, 8.8%
and 16.6%, respectively. There existed a nonlinear relationship between blood pressure value
and the occurrence of stroke assessed by the RCS fitting Cox model. The risk rates for stroke
increased in the patients whose systolic blood pressure (SBP) <110 mmHg or >150 mmHg and
diastolic blood pressure (DBP) <60 mmHg or >90 mmHg. The Cox proportional hazard model by
multivariate analysis found that smoking history (HR 2.32, 95%CI 1.36-3.13, P =0.009), diabetes (HR 2.07, 95%CI 1.18-3.05, P =0.011), atrial fibrillation (HR 1.89, 95%CI 1.16-2.98, P =0.014),
SBP < 110 mmHg (HR 1.62, 95%CI 1.11-2.24, P =0.032) or >150 mmHg (HR 1.79, 95%CI 1.21-
2.72, P =0.013) and carotid artery stenosis (HR 2.47, 95%CI 1.37-4.18, P =0.008) were independent
factors for stroke.
Conclusion There existed the J shaped curve between blood pressure and stroke in the course of
antihypertensive treatment. The incidence of stroke increased in the patients of SBP <110 mmHg or
>150 mmHg.
