Original ArticlePhenotypes of sleep-disordered breathing symptoms to two years of age based on age of onset and duration of symptoms
Introduction
Sleep disordered breathing (SDB), which may range from habitual snoring to obstructive sleep apnea, affects up to 10% of children, with a peak prevalence between two and eight years of age [1], [2], [3]. An increased risk of snoring has been observed among first-born children [4] and children of mothers who smoked during pregnancy [5], while children who were breastfed for more than two months were less likely to develop SDB [6]. Several studies have shown that SDB is more common among atopic children [7], [8] although one study has reported that inner-city snoring children referred for a laboratory sleep study (polysomnography; PSG) were less likely to have asthma [9]. Self-reported proximity to road traffic was associated with self-reported habitual snoring in preschool children although the strength of the association was reduced when controlling for single-parent families and socioeconomic deprivation [8].
We present findings from the Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort study where we sought to determine patterns of SDB symptoms (SDB phenotypes) based on age of onset and duration of symptoms. Childhood SDB may comprise multiple overlapping phenotypes depending on a child’s craniofacial anatomy, tonsil and adenoid growth, body habitus, and presence of rhinitis symptoms [10]. We hypothesized that the different symptom phenotypes may be distinguished by age of onset and duration of symptoms.
Each phenotype may be associated with different genetics (eg, parental history of SDB) and environmental exposures. Increased lymph-adenoid tissue can be triggered by respiratory syncytial virus [11], environmental tobacco smoke [12], [13], and environmental pollutants [14]. We have identified individual factors (eg, atopy, body mass index [BMI], gestational age [GA]) and environmental exposures (eg, breast-feeding, socioeconomic status (SES), daycare attendance) associated with the development of each SDB symptom.
Section snippets
Study participants
CHILD is a longitudinal birth cohort study designed to assess the influence of gene–environment interactions on the development of allergy and asthma. CHILD Edmonton families (N = 822) participated in an add-on study examining the longitudinal relationship between sleep and neurodevelopment. The sleep-related breathing disorder (SRBD) scale, the Brief Infant Sleep questionnaire (BISQ), parental history of obstructive sleep apnea syndrome (OSAS) based on the global sleep assessment questionnaire
Results
Of those with SDB data, three children had severe developmental delay and were excluded from the subsequent trajectory analysis. Over 93% (770/822) of CHILD Edmonton participants had a response to the SRBD for at least one quarterly questionnaire. Among children with SDB data, 68.5% (510/745) of children were Caucasian compared with 55.9% (19/34) of children without data (p > 0.05; Table 1). Mothers of children with SDB data had a mean age of 31.3 years [95% confidence interval (CI): 31.0,
Discussion
We identified four different parent-reported SDB symptom trajectories using data from a population-based birth cohort study; no SDB, early SDB, late SDB, and persistent SDB. Rhinitis and prior daycare attendance were associated with all SDB trajectories. We identified several unique risk factors for each SDB trajectory. Children prescribed GERD medication were more likely to present with early or late SDB symptoms. Children with a maternal history of OSAS were more likely to present with late
Conclusion
Our results suggest that childhood SDB may not be a homogenous disorder. Rather, childhood parent-reported SDB may represent multiple overlapping phenotypes. We identified three parent-reported SDB symptom trajectories to two years using data from the CHILD Edmonton birth cohort. The SDB trajectories were associated with common and unique risk factors in multivariate analyses. Rhinitis was associated with all SDB trajectories while BMI through the first two years was not associated with any of
Acknowledgments
We are grateful to all the families who took part in this study, and the whole CHILD team, which includes interviewers, computer and laboratory technicians, clerical workers, research scientists, volunteers, managers, receptionists and nurses. The Canadian Institutes of Health Research (CIHR) and the Allergy, Genes and Environment (AllerGen) Network of Centres of Excellence provided core support for CHILD. This research was specifically funded by CIHR and the Women and Children’s Health
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Cited by (0)
- 1
These authors contributed equally to this manuscript.
- 2
A complete list of active investigators in the CHILD study is provided in the Supplementary Material.