Effect of cumulative blood pressure exposure on long-term cardiovascular outcomes in the community, a nationwide cohort study

Background

Hypertension is a leading modifiable cause of cardiovascular morbidity and mortality. Current cardiovascular risk prediction models use single blood pressure measurements. However, cumulative blood pressure exposure over prolonged periods of time may better predict incident cardiovascular events.

Methods

We used data from a large national community database to examine the incremental value of 10-year cumulative blood pressure exposure over standard risk based on a single value using the Pooled Cohort Equations (PCE). The index date was set to January 1, 2018, with a 5-year prediction horizon (until December 31, 2022), with 10 years of prior exposure data. Individuals included were 45 years of age or older, had not experienced a previous cardiovascular event, and had at least 3 blood pressure tests in the past 10 years.

The primary exposure was cumulative blood pressure over the 10-year exposure period (between January 1, 2008, and December 31, 2017). This was calculated as the area under the systolic blood pressure curve over 140mmHg in the 10-years before the index date, with values between measurements linearly interpolated. We assessed the model's ability to improve prediction of "Hard CVD" (defined as cardiac mortality, myocardial infarction or stroke), stroke and all cause mortality beyond that achieved by the PCE.

Results

Our cohort included 614,084 individuals who were divided into a derivation set of 428,826 and a validation set of 184,222 individuals. AUROC improved by 0.8% (95% CI: 0, 0.8%), 1.3% (1.0, 1.7%), and 0% (0, 0.1%), and continuous net reclassification improvement was 0.492 (0.458, 0.52), 0.656 (0.62, 0.701), and 0.539 (0.52, 0.559), for the "Hard CVD", stroke, and all-cause mortality outcomes, respectively.

Conclusions

Cumulative blood pressure exposure over 10 years significantly improves the prediction of incident cardiovascular events and mortality above that derived from a single value. Introduction of cumulative blood pressure exposure into electronic health records might facilitate personalized risk prediction in the community.