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Development of predictive models for long-term cardiovascular risk associated with systolic and diastolic blood
Robert J Glynn1, Gilbert J L'Italien, Howard D Sesso
1Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02215-1204, USA. rglynn@rics.bwh.harvard.edu
Insights
Lowering systolic and diastolic blood pressure consistently reduces cardiovascular risk in men and women, with no evidence of a benefit plateau. Systolic blood pressure showed a stronger association with risk in women.
Area of Science:
- Cardiovascular Medicine
- Epidemiology
- Biostatistics
Background:
- Existing cardiovascular risk models often overlook the combined impact of systolic and diastolic blood pressure.
- Some research suggests blood pressure reduction plateaus, limiting benefits.
Purpose of the Study:
- To develop multivariate risk prediction models for cardiovascular risk considering both systolic and diastolic blood pressure.
- To infer the benefits of antihypertensive therapy by quantifying risk reduction from blood pressure lowering.
Main Methods:
- Developed gender-specific Cox regression models using data from the male Physicians' Health Study and female Women's Health Study.
- Included endpoints such as myocardial infarction, stroke, and cardiovascular death.
- Calculated risk reduction estimates from incremental lowering of systolic and diastolic blood pressures.
Main Results:
- Lower blood pressure levels were associated with lower cardiovascular event rates in both genders, without a plateau or J-shaped curve.
- In males, both systolic and diastolic blood pressure significantly predicted events; in females, only systolic blood pressure was a significant predictor.
- Correction for blood pressure measurement error increased risk estimates by approximately 50%.
Conclusions:
- The developed models quantify cardiovascular risk associated with both systolic and diastolic blood pressure.
- Systolic blood pressure differences provided greater relative risk reductions than diastolic blood pressure differences.
- These models can aid in hypertension risk estimation and inferring antihypertensive therapy benefits.
Abstract:
Most existing risk prediction models have not considered the joint contribution of systolic and diastolic blood pressure to cardiovascular risk, and some suggest that there are thresholds below which further reductions of blood pressure yield no additional benefit. We developed multivariate risk prediction models that quantify the risk associated with both systolic and diastolic blood pressure and that can be used to infer the benefits of antihypertensive therapy in populations. Two large clinical trial cohorts, the Physicians' Health Study, composed of 22 071 males (mean age, 53.2 years; median follow-up, 13.0 years), and the Women's Health Study, composed of 39 876 females (mean age, 53.8 years; median follow-up, 6.2 years), were used to develop gender-specific predictive models via Cox regression. End points included myocardial infarction, stroke, coronary artery bypass, angioplasty, and cardiovascular death. Risk reduction estimates were derived by computing reductions associated with incremental lowering of systolic and diastolic blood pressures. In both populations, lower levels of blood pressure predicted lower event rates, with no evidence of a plateau or a J-shaped curve. In males, both systolic and diastolic blood pressures were significantly associated with events (P<0.001), whereas in females, only systolic blood pressure (P<0.001) predicted outcome after multivariate adjustment. Correction for measurement error in blood pressure increased risk estimates by approximately 50%. Differences in systolic blood pressure yielded greater relative risk reductions than did differences in diastolic blood pressure in a combined population of males and females. These predictive models may be useful for risk estimation associated with hypertension in similar populations and may also be used to infer the benefits of antihypertensive therapy.