Use of Long-term Cumulative Blood Pressure in Cardiovascular Risk Prediction Models.

Importance: Long-term cumulative systolic blood pressure (SBP) is significantly associated with increased rates of atherosclerotic cardiovascular disease (ASCVD) development independent of single SBP levels. However, published ASCVD risk prediction algorithms only include currently measured SBP. Objective: To determine whether including long-term (5- and 10-year) cumulative SBP in risk equations improves the predictive ability compared with single SBP measurements. Design, Setting, and Participants: Adults aged 45 to 65 years at the time of risk estimation with at least 20 years of follow-up (5 and 10 years prior to risk estimation and 10 years of event follow-up). The Lifetime Risk Pooling Project included data from the following cohorts: Coronary Artery Risk Development in Young Adults Study, Atherosclerosis Risk in Communities Study, and Framingham Heart Study (both the original and offspring). Exposures: Ten-year ASCVD risk, calculated using the approach of the 2013 American College of Cardiology/American Heart Association 10-year ASCVD risk equations, first with current SBP and then substituting 5- and 10-year cumulative SBP levels. Main Outcomes and Measures: Incident ASCVD events that occurred over 10 years of follow-up, compared with the predicted risks, using the C statistic, net reclassification index at event rate, and the integrated discrimination index.
Results: This study included 11 767 participants with a mean (SD) age of 59.1 (4.7) years at risk estimation. A total of 6873 participants (58%) were women, and 1499 (13%) were African American. In the 10 years of follow-up from risk estimation, 1887 participants (16%) had an ASCVD event. There were no significant improvements in the C statistic when including 5- or 10-year cumulative SBP. However, the addition of cumulative SBP resulted in significant improvements in the net reclassification index at event rate (10-year net reclassification index for men, 0.04 [95% CI, 0.02-0.06]; 10-year net reclassification index for women, 0.03 [95% CI, 0.01-0.06]) and the relative integrated discrimination index (10-year relative integrated discrimination index for men, 0.12; 10-year relative integrated discrimination index for women, 0.10). Conclusions and Relevance: Using long-term measures of cumulative blood pressure, instead of single measurements, can modestly improve the ability of cardiovascular disease risk prediction models to correctly classify individuals in terms of their risk for cardiovascular disease.