Comparison of Frequency of Atherosclerotic Cardiovascular Disease Events Among Primary and Secondary Prevention Subgroups of the Systolic Blood Pressure Intervention Trial

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The Pooled Cohort Equation (PCE) predicts 10-year risk of first-time atherosclerotic cardiovascular disease (ASCVD) events and was incorporated in analyses of a primary and secondary prevention population in the Systolic Blood Pressure Intervention Trial (SPRINT). Whether PCE enhances risk prediction among secondary prevention populations is unknown. We sought to compare ASCVD events by level of PCE-predicted risk among primary and secondary prevention SPRINT populations. SPRINT randomized adults with hypertension and ≥1 CVD risk factor or previous CVD events to systolic blood pressure control targeting <120 mm Hg or 135 to 139 mm Hg. We calculated the hazard ratio (HR) of ASCVD events among secondary versus primary (reference) prevention subgroups overall and by predicted 10-year ASCVD risk categories (<10%, 10% to <20%, 20% to <30%, and ≥30%) and within risk subgroups, comparing to the lowest risk category. Among 8,151 participants, 16% with previous CVD, mean age was 66 years and 35% were women. The HR for ASCVD events overall was 2.51 (1.96, 3.20). HR was 2.97 (1.47, 5.99) among <10% 10-year risk and 2.23 (1.38, 3.59) among ≥30% risk. Within subgroups comparing ≥30% to <10% risk (reference) categories, the HR was 2.85 (1.76, 4.63) for primary and 2.14 (1.07, 4.30) for the secondary prevention. In conclusion, history of previous events was a potent risk factor for subsequent ASCVD events. The PCE does not enhance risk prediction among secondary prevention populations and may differentially underestimate risk in secondary prevention populations with lowest predicted risk.

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Methods

SPRINT was an open label randomized controlled trial conducted at 102 centers in the United States and its territories. Eligible adults with systolic hypertension (systolic BP 130 to 180 mm Hg) and ≥1 risk factor for cardiovascular disease (CVD) or previous CVD but without diabetes mellitus or previous stroke. Details of SPRINT and the primary outcomes have been published elsewhere.7,8 Risk factors for CVD included clinical CVD (excluding stroke), subclinical CVD, chronic kidney disease with

Results

Of the 9,361 SPRINT participants, we excluded 52 (0.5%) for missing data required for the PCE and 1,158 (12%) for age ≥80 years. The final analytic population was 8,151 participants, 6,874 without previous CVD (84%) and 1,127 with previous ASCVD (16%). Median (interquartile range) follow-up was 3.2 (2.7 to 3.8) years. Characteristics of trial participants by primary and secondary prevention populations and by 10-year risk range appear in Table 1. Overall mean ± standard deviation (SD) age was

Discussion

We observed a 2.51-fold increased hazard of ASCVD events among SPRINT participants in the secondary prevention population when compared with the primary prevention population. When compared by category of PCE-predicted 10-year ASCVD risk, the secondary prevention population experienced more incident ASCVD events across the spectrum of predicted risk than the primary prevention population. The burden of events experienced in the secondary prevention population was largest among those with the

Disclosures

The authors have no conflicts of interest to disclose.

Acknowledgment

The authors would like to thank participants and investigators of SPRINT. The authors thank the staff of the NHLBI BioLINCC for providing support for this analysis.

References (19)

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Registration Number

ClinicalTrials.gov: NCT01206062.

Suggested Tweet: Prior CVD is a major risk for subsequent events in SPRINT, even when accounting for baseline Pooled Cohort Equation-predicted risk.

Funding: This work was sponsored by the Department of Medicine at the Larner College of Medicine. SPJ is sponsored by an NHLBI career development award (K23HL135273), Boston, MA.

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