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JVR Marsh, J Coresh, M Szklo, Johns Hopkins University Bloomberg,
School of Public Health
The relative importance of systolic blood pressure (SBP), diastolic
blood pressure (DBP), pulse pressure (PP), and mean arterial pressure
(MAP) in heart disease risk is of increasing interest. This prospective
study compared risks of myocardial infarction (MI) associated with
separate and joint blood pressure components in a cohort of 14,488
adults without history of MI. Hospitalized MI incidence (n=306) was
determined by linkage to a community surveillance program in Washington
County, MD (mean follow-up = 7.6 years). Hazard ratios (HRs) for MI
associated with continuous and categorical blood pressure components
were estimated with Cox regression, adjusting for sex, age, body mass
index, cholesterol, diabetes medications, antihypertensive medications,
smoking and education. Comparing single blood pressure components,
SBP and MAP were the best predictors of MI; neither PP nor DBP significantly
improved on the predictive power of SBP or MAP in likelihood ratio
tests (p-value > 0.05). Considering SBP and DBP (mm Hg) jointly,
compared to individuals with SBP < 120 and DBP < 80, those with
SBP >= 140 and DBP < 80 had the highest risk of MI of all combinations
(see table). Among 3,538 individuals with high SBP (SBP >= 140),
everyone with low DBP (DBP < 80, n=470) also had high PP (>=
60 mm Hg), but only 22% of those with high PP (n=2,156) also had low
DBP. Low DBP (HR=1.8, 95% Confidence Interval (CI): 1.1,2.9) predicted
MI risk better than high PP (HR=1.05, 95% CI: 0.7,1.6) when modeled
simultaneously in the high SBP group. This study emphasizes the importance
of high SBP in predicting MI risk and suggests that low DBP provides
a better measure of increased risk than high PP among individuals
with high SBP.
| Hazard
Ratios & 95% CIs for SBP & DBP (mm Hg) |
| DBP |
SBP
<120 |
SBP
120-139 |
SBP
140+ |
| <80 |
1.0 (reference) |
1.8 (1.0,3.0) |
4.7 (2.6,8.6) |
| 80-89 |
2.0 (1.0,4.0) |
2.0 (1.2,3.3) |
2.5 (1.5,4.2) |
| 90+ |
zero events |
2.7 (1.5,4.8) |
2.7 (1.6,4.5) |
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