Ambulatory Hypertension Subtypes and 24-Hour Systolic and Diastolic Blood Pressure as Distinct Outcome Predictors in 8341 Untreated People Recruited From 12 Populations
What is the risk associated with 24-hour ambulatory diastolic blood pressure (DBP) compared to 24-hour systolic BP (SBP)?
Data from the International Database on Ambulatory blood pressure in relation to Cardiovascular Outcomes (IDACO) were used for the present analysis. Participants under the age of 18 years were excluded, as were those taking medication for hypertension (HTN). Twenty-four hour BPs and health outcomes were collected among subjects (5,489 Europeans [65.8%], 1,280 Asians [15.3%], and 1,572 South Americans [18.9%]) randomly recruited. Outcomes were assessed from appropriate sources within each country. Fatal and nonfatal stroke did not include transient ischemic attacks. Coronary events encompassed death from ischemic heart disease, sudden death, nonfatal myocardial infarction, and coronary revascularization. Cardiac events comprised coronary endpoints and fatal and nonfatal heart failure. Hospitalizations for unstable angina were coded as ischemic heart disease. In analyses of combined outcomes, first event was the only event considered within each disease cluster.
A total of 8,341 participants were included, with an age range from 18-94 years (mean age, 50.8 years; 46.6% women). At enrollment, 2,474 participants (29.7%) were smokers and 4,061 (48.7%) reported intake of alcohol. In the whole study population, conventional BP averaged (± standard deviation [SD]) 128.7 ± 21.4 mm Hg systolic and 78.6 ± 11.3 mm Hg diastolic, while the 24-hour ambulatory BP was 122.1 ± 13.5 mm Hg systolic and 73.1 ± 8.2 mm Hg diastolic. Over 11.2 years (median), 927 (11.1%) participants died, 356 (4.3%) from cardiovascular causes. A total of 744 (8.9%) experienced a fatal or nonfatal cardiovascular disease event. Isolated diastolic HTN (DBP24 ≥80 mm Hg) did not increase the risk of total mortality, cardiovascular disease mortality, or stroke (hazard ratio [HRs], ≤1.54; p ≥ 0.18), but was associated with a higher risk of fatal combined with nonfatal cardiovascular, cardiac, or coronary events (HRs, ≤1.75; p ≤ 0.0054). Isolated systolic HTN (SBP24 ≥130 mm Hg) and mixed diastolic plus systolic HTN were associated with increased risks of all these endpoints (p ≤ 0.0012). Below the age of 50, DBP24 was the main driver of risk, reaching significance for total (HR for 1-SD increase, 2.05; p = 0.0039) and cardiovascular mortality (HR, 4.07; p = 0.0032) and for all CVD endpoints combined (HR, 1.74; p = 0.039) with a nonsignificant contribution of SBP24 (HR ≤0.92; p ≥ 0.068); above the age of 50, SBP24 predicted all endpoints (HR ≥1.19; p ≤ 0.0002) with a nonsignificant contribution of DBP24 (p ≥ 0.10). The interactions of age with SBP24 and DBP24 were significant for all cardiovascular and coronary events (p ≤ 0.043).
The investigators concluded the risks conferred by DBP24 and SBP24 are age dependent. DBP24 and isolated diastolic HTN are associated with coronary events below the age of 50. In contrast, above the age of 50, SBP24 and isolated systolic and mixed HTN are the predominant risk factors.
These data demonstrate the risk associated with both diastolic and systolic HTN on a global level. Appropriate diagnosis and treatment of both diastolic and systolic HTN is likely to have a significant impact on the global burden of cardiovascular disease.
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