China Stroke Primary Prevention Trial: Visit-to-Visit Systolic Blood Pressure Variability Is an Independent Predictor of Primary Stroke in Hypertensive Patients

Abstract

Background: The optimal range of blood pressure variability remains unclear. We aimed to stratify the degree of risk of stroke based on visit-to-visit systolic blood pressure (SBP) variability in a large Chinese hypertensive population in 32 communities.

Methods and results: We retrospectively analyzed the data of 20 702 hypertensive patients from the China Stroke Primary Prevention Trial. The participants were randomized into 2 treatment groups to receive either enalapril or enalapril plus folic acid. Their blood pressures were measured every 3 months. The outcome was the first stroke. Three parameters of SBP variability were calculated: standard deviation, coefficient of variation, and average real variability. The records of first 4, 6, 8, 10 and 12 visits at which SBP was measured were used to calculate SBP variability and to predict subsequent stroke risk in adjusted Cox regression models. After median follow-up of 4.5 years, 597 patients had experienced stroke. Visit-to-visit SBP variability was an independent predictor of subsequent stroke (eg, the hazard ratio for the highest quintile of average real variability [22.67-61.07 mm Hg] over 6 visits was 1.55, 95% CI 1.07-2.25, P=0.021), independent of mean SBP over the follow-up period. Its value was more predictive when more blood pressure records were used.

Conclusions: Visit-to-visit SBP variability is an independent predictor of primary stroke in Chinese hypertensive patients. This predictive value depends on the number of blood pressure measurements used to calculate variability but is independent of mean SBP.

Clinical trial registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00794885.

Keywords: hypertension; stroke; systolic blood pressure variability.

Figure 1

Flow of participants in the analysis of BPV over 6 visits. BPV indicates blood pressure variability; CSPPT, China Stroke Primary Prevention Trial.

Figure 2

Hazard ratios for risk of subsequent stroke by quintiles of visit‐to‐visit systolic blood pressure standard deviation, coefficient of variation and average real variability over 6 visits, with the first quintile (Q1) as the reference. The hazard ratios (95% CI) for risks of subsequent stroke in a crude model by quintiles of visit‐to‐visit systolic blood pressure variability parameters over the first 6 visits. A, Standard deviation. B, Coefficient of variation. C, Average real variability. The first quintile of each parameter is the reference category. Numbers of subsequent stroke events by quintiles are given in Table S10; Q1 to Q5, each quintile of the same parameters.