Office or Ambulatory BP for Predicting CV Events
What is the added value of: 1) 24-hour ambulatory blood pressure (ABP) relative to office blood pressure, and 2) night-time (range 10 p.m.-4 a.m.) ambulatory blood pressure (night ABP) relative to daytime (range 8 a.m.-8 p.m.) (day ABP) for 10-year person-specific absolute risks of fatal and nonfatal cardiovascular events (CVEs)?
A total of 7,927 participants were included from the International Database on ABP Monitoring in relation to CV outcomes. The data set contained multiple general population cohorts. The analysis included summarized 10-year predicted risks of any CVE in subgroups defined by age, known history of CV diseases, known diabetes, ongoing antihypertensive treatment, and hypertension. A cause-specific Cox regression was used to predict 10-year person-specific absolute risks of fatal and nonfatal CVEs. Discrimination of 10-year outcomes was assessed by time-dependent area under the receiver operating characteristic curve (AUC).
Mean (standard deviation) age was 57.2 (14.3) years, and 55% were male. For the entire group, the mean office BP in mm Hg was 134.8 (23.8), 24-hour ABP 124.9 (14.5), day ABP 131.1 (15.5), and night ABP 113.8 (15.9). During the follow-up period, 563 participants died from CVEs and 758 died from non-CVEs. Further, 1,173 were diagnosed with a fatal or nonfatal CVE. The median follow-up period ranged from 9.1 to 17 years (Q1–Q3, 12.1-12.2). No differences in predicted risks were observed when comparing office BP and 24-hour ABP. The median difference in 10-year risks (first; third quartile) was -0.01% (-0.3%; 0.1%) for CV mortality and -0.1% (-1.1%; 0.5%) for CVEs. The difference in AUC (95% confidence interval) was 0.65% (0.22–1.08%) for CV mortality and 1.33% (0.83–1.84%) for CVEs. Comparing day ABP and night ABP, the median difference in 10-year risks was 0.002% (-0.1%; 0.1%) for CV mortality and -0.01% (-0.5%; 0.2%) for CVEs. The difference in AUC was 0.10% (-0.08 to 0.29%) for CV mortality and 0.15% (-0.06 to 0.35%) for CVEs.
Ten-year predictions obtained from ABP are similar to predictions from office BP when utilizing person-specific risk. Night-time BP does not improve 10-year predictions obtained from daytime measurements. For an otherwise healthy population, sufficient prognostic accuracy of CV risks can be achieved with office BP.
The study was conducted in the same cohort that had concluded the added value of night ABP for predicting 10-year CVE rates. The difference in this study was the application of person-specific 10-year absolute risks of CV outcomes.
Keywords: Antihypertensive Agents, Blood Pressure, Blood Pressure Determination, Blood Pressure Monitoring, Ambulatory, Diabetes Mellitus, Hypertension, Inflammation, Primary Prevention, Risk, Vascular Diseases
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