Abstract
The risk of atherosclerotic cardiovascular disease (ASCVD) at currently defined normal systolic blood pressure (SBP) levels in persons without ASCVD risk factors based on current definitions is not well defined. To examine the association of SBP levels with coronary artery calcium and ASCVD in persons without hypertension or other traditional ASCVD risk factors based on current definitions. A cohort of 1457 participants free of ASCVD from the Multi-Ethnic Study of Atherosclerosis who were without dyslipidemia (low-density lipoprotein cholesterol level ≥160 mg/dL or high-density lipoprotein cholesterol level <40 mg/dL), diabetes (fasting glucose level ≥126 mg/dL), treatment for hyperlipidemia or diabetes, or current tobacco use, and had an SBP level between 90 and 129 mm Hg. Participants receiving hypertension medication were excluded. Coronary artery calcium was classified as absent or present and adjusted hazard ratios (aHRs) were calculated for incident ASCVD. The study was conducted from March 27, 2018, to February 12, 2020.
Generated Summary
This original investigation, published in JAMA Cardiology, explores the association between normal systolic blood pressure (SBP) levels and cardiovascular disease (CVD) risk factors in individuals without traditional risk factors such as hypertension. The study, conducted from March 27, 2018, to February 12, 2020, involved a cohort of 1457 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). The research aimed to determine if SBP levels, within the currently defined normal range (90-129 mm Hg), correlated with coronary artery calcium (CAC) and incident CVD events in the absence of other known risk factors. The study employed a prospective cohort design, examining SBP as the primary exposure and CAC and incident CVD events as the main outcomes. The analysis included adjustments for age, sex, race/ethnicity, and other relevant risk factors. This research sought to understand whether there is a threshold below which SBP is not associated with increased risk, and if population-level prevention strategies might be beneficial for individuals with normal SBP levels but without other traditional CVD risk factors.
Key Findings & Statistics
- Participant Characteristics: The study included 1457 participants. The mean (SD) age was 58.1 (9.8) years, and 894 participants (61.4%) were women.
- SBP Levels and Traditional Risk Factors: There was an increase in traditional ASCVD risk factors, coronary artery calcium, and incident ASCVD events with increasing SBP levels.
- Every 10-mm Hg Increase in SBP: The adjusted hazard ratio (aHR) for ASCVD was 1.53 (95% CI, 1.17-1.99) for every 10-mm Hg increase in SBP levels.
- SBP Levels 90 to 99 mm Hg: Compared with persons with SBP levels 90 to 99 mm Hg, the aHR for ASCVD risk was 3.00 (95% CI, 1.01-8.88) for SBP levels 100 to 109 mm Hg.
- SBP Levels 110 to 119 mm Hg: The aHR for SBP levels 110 to 119 mm Hg was 3.10 (95% CI, 1.03-9.28).
- SBP Levels 120 to 129 mm Hg: The aHR for SBP levels 120 to 129 mm Hg was 4.58 (95% CI, 1.47-14.27).
- 10-year ASCVD Risk: The median 10-year pooled cohort equations ASCVD risk was 3.0% (interquartile range, 1.1%-6.7%).
- ASCVD Events: Over a mean follow-up of 14.5 (3.9) years, there were 94 incident ASCVD events. Among participants in our study with an SBP level less than 110 mm Hg, the median 10-year ASCVD risk was 1.7% (interquartile range, 0.7%-4.5%).
- Coronary Artery Calcium (CAC): The rate of incident ASCVD events per 1000 person-years also increased in a graded manner with increasing SBP levels, with unadjusted SBP level 90 to 99 mm Hg, 1.3; 100 to 109 mm Hg, 4.0; 110 to 119 mm Hg, 4.5; and 120 to 129 mm Hg, 8.3.
- HR for ASCVD for Every 10-mm Hg Increase: There was a 53% higher risk for incident ASCVD for every 10-mm Hg increase in SBP level, with an HR of 1.52 (95% CI, 1.15-2.00) using model 2 adjustment variables.
Other Important Findings
- The proportion of participants with coronary artery calcium and diffuse coronary artery calcium increased in a stepwise manner with increasing SBP levels.
- The study found a significant increase in the risk for incident ASCVD across SBP values when SPB was modeled as a continuous variable.
- Overall, the study observed an increase in the mean values of traditional ASCVD risk factors with increasing SBP levels.
Limitations Noted in the Document
- The study’s limitations include the use of only a baseline SBP level measurement.
- There was a significant age difference between the lower and higher SBP level groups.
- The study focused on traditional ASCVD risk factors based on current definitions and did not include behavioral risk factors such as diet and physical activity.
- The study acknowledges that there may be residual confounding not accounted for by their adjusted modeling methods.
Conclusion
The study’s findings underscore the importance of primordial prevention for maintaining optimal SBP levels and other traditional ASCVD risk factors. The research suggests that, even in healthy adults without hypertension or other traditional risk factors, a stepwise increase in SBP levels is associated with an increased risk of coronary artery calcium and incident ASCVD. The association between SBP level, coronary artery calcium, and ASCVD events was present at an SBP level below the current hypertension definition (90 mm Hg). The authors emphasize that the levels of other traditional ASCVD risk factors were higher with higher SBP levels, and that there may be residual confounding not accounted for by the adjusted modeling methods. Primordial prevention strategies should focus on broad risk factor control rather than any single ASCVD risk factor. The study results highlight the need for further implementation research on the primordial prevention of SBP level increases and other traditional ASCVD risk factors. The authors suggest that, in otherwise healthy adults, individuals with an SBP level between 90 and 99 mm Hg have a low cardiovascular disease event rate. The findings imply that the continuum of risk associated with SBP level is graded with no nadir or J-point observed for SBP levels as low as 90 mm Hg. The study supports the importance of primordial prevention for SBP level increases along with other traditional ASCVD risk factors, which generally display similar trajectories of graded increase in risk within values traditionally considered to be normal. The authors note that their findings may have implications for primordial prevention strategies to maintain optimal SBP for several reasons. The data suggest that, in otherwise healthy adults, individuals with an SBP level between 90 and 99 mm Hg have a low cardiovascular disease event rate, and the lowest prevalence of coronary artery calcium and lowest incident rate of ASCVD. The authors also point out that the continuum of risk associated with SBP level is graded with no nadir or J-point observed for SBP levels as low as 90 mm Hg. Finally, the authors observed that the levels of other traditional ASCVD risk factors were higher with higher SBP levels and that there may be residual confounding not accounted for by our adjusted modeling methods.