title: Validity of (Ultra-)Short Recordings for Heart Rate Variability Measurements.
abstract: OBJECTIVE
  In order to investigate the applicability of routine 10s electrocardiogram (ECG) recordings for time-domain heart rate variability (HRV) calculation we explored to what extent these (ultra-)short recordings capture the "actual" HRV.
  
  
  METHODS
  The standard deviation of normal-to-normal intervals (SDNN) and the root mean square of successive differences (RMSSD) were measured in 3,387 adults. SDNN and RMSSD were assessed from (ultra)short recordings of 10s(3x), 30s, and 120s and compared to 240s-300s (gold standard) measurements. Pearson's correlation coefficients (r), Bland-Altman 95% limits of agreement and Cohen's d statistics were used as agreement analysis techniques.
  
  
  RESULTS
  Agreement between the separate 10s recordings and the 240s-300s recording was already substantial (r = 0.758-0.764/Bias = 0.398-0.416/d = 0.855-0.894 for SDNN; r = 0.853-0.862/Bias = 0.079-0.096/d = 0.150-0.171 for RMSSD), and improved further when three 10s periods were averaged (r = 0.863/Bias = 0.406/d = 0.874 for SDNN; r = 0.941/Bias = 0.088/d = 0.167 for RMSSD). Agreement increased with recording length and reached near perfect agreement at 120s (r = 0.956/Bias = 0.064/d = 0.137 for SDNN; r = 0.986/Bias = 0.014/d = 0.027 for RMSSD). For all recording lengths and agreement measures, RMSSD outperformed SDNN.
  
  
  CONCLUSIONS
  Our results confirm that it is unnecessary to use recordings longer than 120s to obtain accurate measures of RMSSD and SDNN in the time domain. Even a single 10s (standard ECG) recording yields a valid RMSSD measurement, although an average over multiple 10s ECGs is preferable. For SDNN we would recommend either 30s or multiple 10s ECGs. Future research projects using time-domain HRV parameters, e.g. genetic epidemiological studies, could calculate HRV from (ultra-)short ECGs enabling such projects to be performed at a large scale.
authors.affiliation: Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: M Loretto
authors.initials: ML
authors.lastname: Munoz
authors.affiliation: Department of Vascular Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Arie
authors.initials: A
authors.lastname: van Roon
authors.affiliation: Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Interdisciplinary Center Psychopathology and Emotion regulation (ICPE), Department of Psychiatry, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Harriëtte
authors.initials: H
authors.lastname: Riese
authors.affiliation: Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Chris
authors.initials: C
authors.lastname: Thio
authors.affiliation: Department of Vascular Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Emma
authors.initials: E
authors.lastname: Oostenbroek
authors.affiliation: Department of Vascular Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Iris
authors.initials: I
authors.lastname: Westrik
authors.affiliation: Department of Biological Psychology, VU University Amsterdam & Institute for Health and Care Research (EMGO+), VU Medical Center, Amsterdam, The Netherlands.
authors.forename: Eco J C
authors.initials: EJ
authors.lastname: de Geus
authors.affiliation: Department of Internal Medicine, Division of Nephrology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Ron
authors.initials: R
authors.lastname: Gansevoort
authors.affiliation: Department of Vascular Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Joop
authors.initials: J
authors.lastname: Lefrandt
authors.affiliation: Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Ilja M
authors.initials: IM
authors.lastname: Nolte
authors.affiliation: Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Harold
authors.initials: H
authors.lastname: Snieder
mesh_terms: D000328:Adult; D003710:Demography; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013223:Statistics as Topic; D013997:Time Factors