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Heart rate variability (HRV) is a non-invasive quantitative marker of cardiac autonomic function derived from continuous electrocardiogram (ECG) recordings. Normative HRV values and development factors have not been established in pediatric populations. The objective was to derive referent time- and frequency-domain HRV values for a population-based sample of children. Children aged 9-11 years ( N = 1,036) participated in the Québec Longitudinal Study of Child Development cohort cardiovascular health screening. Registered nurses measured anthropometrics (height, weight) and children wore an ambulatory Holter monitor to continuously record an ECG signal. HRV variables included time (SDNN, pNN50, RMSSD, SDANN) and frequency (HF, LF, LF/HF ratio) domain variables. Normative HRV values, stratified by age, sex, and heart rate, are presented. Greater heart rate ( β = −0.60, R = 0.39), pubertal maturation ( β = −0.11, R = 0.01), later ECG recording times ( β = −0.19, R = 0.07), and higher diastolic blood pressure ( β = −0.11, R = 0.01) were significantly associated with reduced HRV in 10-year-old children. The normative HRV values permit clinicians to monitor, describe, and establish pediatric nosologies in primary care and research settings, which may improve treatment of diseases associated with HRV in children. By better understanding existing values, the practical applicability of HRV among clinicians will be enhanced. Lastly, developmental (e.g., puberty) and procedural (e.g., recording time) factors were identified that will improve recording procedures and interpretation of results. [ABSTRACT FROM AUTHOR]

Child dental caries (i.e., cavities) are a major preventable health problem in most high-income countries. The aim of this study was to compare the extent of inequalities in child dental caries across four high-income countries alongside their child oral health policies. Coordinated analyses of data were conducted across four prospective population-based birth cohorts (Australia, n = 4085, born 2004; Québec, Canada, n = 1253, born 1997; Rotterdam, the Netherlands, n = 6690, born 2002; Southeast Sweden, n = 7445, born 1997), which enabled a high degree of harmonization. Risk ratios (adjusted) and slope indexes of inequality were estimated to quantify social gradients in child dental caries according to maternal education and household income. Children in the least advantaged quintile for income were at greater risk of caries, compared to the most advantaged quintile: Australia: AdjRR = 1.18, 95%CI = 1.04–1.34; Québec: AdjRR = 1.69, 95%CI = 1.36–2.10; Rotterdam: AdjRR = 1.67, 95%CI = 1.36–2.04; Southeast Sweden: AdjRR = 1.37, 95%CI = 1.10–1.71). There was a higher risk of caries for children of mothers with the lowest level of education, compared to the highest: Australia: AdjRR = 1.18, 95%CI = 1.01–1.38; Southeast Sweden: AdjRR = 2.31, 95%CI = 1.81–2.96; Rotterdam: AdjRR = 1.98, 95%CI = 1.71–2.30; Québec: AdjRR = 1.16, 95%CI = 0.98–1.37. The extent of inequalities varied in line with jurisdictional policies for provision of child oral health services and preventive public health measures. Clear gradients of social inequalities in child dental caries are evident in high-income countries. Policy related mechanisms may contribute to the differences in the extent of these inequalities. Lesser gradients in settings with combinations of universal dental coverage and/or fluoridation suggest these provisions may ameliorate inequalities through additional benefits for socio-economically disadvantaged groups of children. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to examine social gradients in ADHD during late childhood (age 9–11 years) using absolute and relative relationships with socioeconomic status exposure (household income, maternal education) during early childhood (<5 years) in seven cohorts from six industrialised countries (UK, Australia, Canada, The Netherlands, USA, Sweden). Methods: Secondary analyses were conducted for each birth cohort. Risk ratios, pooled risk estimates, and absolute inequality, measured by the Slope Index of Inequality (SII), were estimated to quantify social gradients in ADHD during late childhood by household income and maternal education measured during early childhood. Estimates were adjusted for child sex, mother age at birth, mother ethnicity, and multiple births. Findings: All cohorts demonstrated social gradients by household income and maternal education in early childhood, except for maternal education in Quebec. Pooled risk estimates, relating to 44,925 children, yielded expected gradients (income: low 1.83(CI 1.38,2.41), middle 1.42(1.13,1.79), high (reference); maternal education: low 2.13(1.39,3.25), middle 1.42(1.13,1.79)). Estimates of absolute inequality using SII showed that the largest differences in ADHD prevalence between the highest and lowest levels of maternal education were observed in Australia (4% lower) and Sweden (3% lower); for household income, the largest differences were observed in Quebec (6% lower) and Canada (all provinces: 5% lower). Conclusion: Findings indicate that children in families with high household income or maternal education are less likely to have ADHD at age 9–11. Absolute inequality, in combination with relative inequality, provides a more complete account of the socioeconomic status and ADHD relationship in different high-income countries. While the study design precludes causal inference, the linear relation between early childhood social circumstances and later ADHD suggests a potential role for policies that promote high levels of education, especially among women, and adequate levels of household income over children's early years in reducing risk of later ADHD. [ABSTRACT FROM AUTHOR]