Differences in night-time and daytime ambulatory blood pressure when diurnal periods are defined by self-report, fixed-times, and actigraphy: Improving the Detection of Hypertension study

Academic Article


  • Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved. Objectives: To determine whether defining diurnal periods by self-report, fixed-time, or actigraphy produce different estimates of night-time and daytime ambulatory blood pressure (ABP). Methods: Over a median of 28 days, 330 participants completed two 24-h ABP and actigraphy monitoring periods with sleep diaries. Fixed night-time and daytime periods were defined as 0000-0600 h and 1000-2000 h, respectively. Using the first ABP period, within-individual differences for mean night-time and daytime ABP and kappa statistics for night-time and daytime hypertension (systolic/diastolic ABP≥120/70 mmHg and ≥135/85 mmHg, respectively) were estimated comparing self-report, fixed-time, or actigraphy for defining diurnal periods. Reproducibility of ABP was also estimated. Results: Within-individual mean differences in night-time systolic ABP were small, suggesting little bias, when comparing the three approaches used to define diurnal periods. The distribution of differences, represented by 95% confidence intervals (CI), in night-time systolic and diastolic ABP and daytime systolic and diastolic ABP was narrowest for self-report versus actigraphy. For example, mean differences (95% CI) in night-time systolic ABP for self-report versus fixed-time was -0.53 (-6.61, +5.56) mmHg, self-report versus actigraphy was 0.91 (-3.61, +5.43) mmHg, and fixed-time versus actigraphy was 1.43 (-5.59, +8.46) mmHg. Agreement for night-time and daytime hypertension was highest for self-report versus actigraphy: kappa statistic (95% CI) = 0.91 (0.86,0.96) and 1.00 (0.98,1.00), respectively. The reproducibility of mean ABP and hypertension categories was similar using each approach. Conclusion: Given the high agreement with actigraphy, these data support using self-report to define diurnal periods on ABP monitoring. Further, the use of fixed-time periods may be a reasonable alternative approach.
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    Digital Object Identifier (doi)

    Author List

  • Booth JN; Muntner P; Abdalla M; Diaz KM; Viera AJ; Reynolds K; Schwartz JE; Shimbo D
  • Start Page

  • 235
  • End Page

  • 243
  • Volume

  • 34
  • Issue

  • 2