The modifying effects of HS-CRP on the association between blood pressure and stroke risk in a non-hypertensive population: A prospective cohort study.

Background And Aim: While blood pressure (BP) and high-sensitivity C-reactive protein (HS-CRP) are established stroke risk factors, their synergistic effects in normotensive populations remain unclear. This study investigates HS-CRP's modifying role in BP-stroke risk associations among Chinese adults without hypertension.

Methods And Results: This study included 4509 participants aged ≥45 years from the China Health and Retirement Longitudinal Study (CHARLS). Blood samples and blood pressure measurements within the normal range (SBP/DBP <140/90 mm Hg) were collected at baseline and stroke events were collected during 9 years of follow-up. Multivariate Cox proportional hazards regression models assessed the association between elevated BP and stroke risk stratified by HS-CRP levels. During the 9-year follow-up, 316 participants had a stroke event. In the high HS-CRP levels, higher SBP [hazard ratio (HR):1.40, 95 % confidence interval (CI): 1,19-1,64], higher DBP (HR:1.32, 95 % CI:1.13-1.56), and higher MAP (HR:1.39, 95 % CI:1.18-1.64) were associated with the risk of stroke (all P<0.001). Linear dose-response associations were found between SBP, DBP, MAP, and stroke risk (P<0.001). However, in the low HS-CRP levels, higher BP was not associated with stroke risk. Linear dose-response associations weren't found between BP and stroke risk. There was an interaction between HS-CRP and SBP on the risk of future stroke events (P = 0.006).

Conclusions: Elevated BP within normal ranges (SBP, DBP, MAP) was associated with an increased risk of stroke in only high HS-CRP levels. HS-CRP may be an important factor affecting the association between elevated normal BP and stroke risk.