title: 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.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors: aDepartment of Epidemiology, University of Alabama at Birmingham, Birmingham, AlabamabDepartment of Medicine, Center for Behavioral Cardiovascular Health, Columbia University Medical Center, New York City, New YorkcDepartment of Family Medicine and Hypertension Research Program, University of North Carolina School of Medicine, Chapel Hill, North CarolinadDepartment of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, CaliforniaeApplied Behavioral Medicine Research Institute, Stony Brook University, Stony Brook, New York, USA.
authors: John N
authors: JN
authors: Booth
authors: Paul
authors: P
authors: Muntner
authors: Marwah
authors: M
authors: Abdalla
authors: Keith M
authors: KM
authors: Diaz
authors: Anthony J
authors: AJ
authors: Viera
authors: Kristi
authors: K
authors: Reynolds
authors: Joseph E
authors: JE
authors: Schwartz
authors: Daichi
authors: D
authors: Shimbo
mesh_terms: D056044:Actigraphy; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm; D003971:Diastole; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009519:New York City / Q000453:epidemiology; D015203:Reproducibility of Results; D057566:Self Report; D012890:Sleep; D013599:Systole