Abstract

Measures of heart rate variability (HRV) are commonly used in longitudinal studies among infants, children, and adolescents as an indicator of autonomic cardiovascular control. However, the psychometric properties of pediatric HRV measures have yet to be established. This thesis examined the psychometrics of time- and frequency-domain HRV measures among infants and youth through two complementary studies. The first study was a systematic review and meta-analysis of 46 studies that evaluated how study methodology (study protocol, sample characteristics, ECG signal acquisition and pre-processing, HRV analyses) affects HRV test-retest reliability. HRV displayed moderate reliability overall across infant/toddler (Mage <5 yrs; Fisher’s Z = 0.42) and child/adolescent groups (Mage 5–18 yrs; Z = 0.64); reliability among infant/toddler studies was relatively more sensitive to examined a priori moderator variables. The second study examined temporal stability of HRV measures obtained from children (Mage 9 yrs) participating in a large, longitudinal cohort study (N = 632) within Quebec. Results indicated that HRV is a moderately stable individual difference in children (ICCrange = 0.74–0.85; rrange = 0.67–0.75), and stability was robust to initial differences in, and developmental changes among demographic (age, puberty), cardiovascular (blood pressure), anthropometric (height, adiposity indices), and physical activity (e.g., weekday/end screen time) covariates. However, stability of HRV measures reflecting parasympathetic (rMSSD, pNN50, HF) activity was augmented following statistical control of time-varying heart rate measures. Together, this thesis contributes original knowledge regarding the psychometrics of pediatric HRV measures. Pertinent methodological and intra-individual factors recommended for consideration by future researchers are discussed.