title: Measures of cardiovascular autonomic nervous function: agreement, reproducibility, and reference values in middle age and elderly subjects.
abstract: OBJECTIVE
  Currently, three categories of cardiovascular autonomic nervous function measures are used: classic Ewing-test measures, measures of heart-rate variability (HRV), and measures of baroreflex sensitivity (BRS). Little is known about the agreement between these measures, and reference and reproducibility values for these measures have not been reported within the same group.
  
  
  METHODS
  As part of the Hoorn Study, 631 subjects aged 50 to 75 participated in a study of autonomic nervous function. Cardiac cycle duration (RR interval) and continuous finger arterial pressure were measured under three conditions: during spontaneous breathing, during six deep breaths over 1 min, and during an active change in position from lying to standing. From these readings, ten measures of autonomic function were assessed (mean heart rate, three Ewing test measures, five HRV measures and one BRS measure).
  
  
  RESULTS
  Regression analysis in a healthy subgroup (n=191) showed sex differences for two of the ten measures and seven measures decreased with age. Therefore, appropriate age-specific and sex-specific reference values were calculated. Reproducibility (n=39) of most measures was moderate, with a reliability coefficient of around 50%. Agreement between the measures of autonomic nervous function varied greatly, between 0% and 87%. The HRV-power ratio measure and the blood pressure changes in the lying-to-standing test showed the lowest agreement with all other measures.
  
  
  CONCLUSIONS
  This study provides age-specific and sex-specific reference values for a wide range of different autonomic function measures in an elderly population. Agreement among the different measures varied widely and reproducibility was only moderate.
authors.affiliation: Department of Clinical Physics and Informatics, Vrije Universiteit medical centre, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Gerritsen
authors.forename: B J
authors.initials: BJ
authors.lastname: TenVoorde
authors.forename: J M
authors.initials: JM
authors.lastname: Dekker
authors.forename: R
authors.initials: R
authors.lastname: Kingma
authors.forename: P J
authors.initials: PJ
authors.lastname: Kostense
authors.forename: L M
authors.initials: LM
authors.lastname: Bouter
authors.forename: R M
authors.initials: RM
authors.lastname: Heethaar
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002320:Cardiovascular Physiological Phenomena; D005260:Female; D006321:Heart / Q000294:innervation / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D012016:Reference Values; D015203:Reproducibility of Results