Risk Factors and Natural History of Habitual Snoring

Abstract and Introduction

Study objective: It has been suggested that habitual snoring (HS) has adverse health outcomes in children. We aimed to identify risk factors for HS and determine its natural history in primary school children.
Design: Cross-sectional, population-based cohort study.
Setting: Twenty-seven primary schools located within the city limits of Hannover, Germany.
Participants: Third-grade primary school children.
Measurements and results: Snoring frequency and potential risk factors were investigated using parental questionnaires. Unadjusted and adjusted odds ratios (ORs) for HS and their 95% confidence intervals (CIs) were calculated. One year after the initial contact, snoring status was re-evaluated in habitual snorers. In total, 1,760 children were contacted, and 1,144 parents and their children (49% were girls) agreed to participate and returned a completed questionnaire. A body mass index ≥ 90th percentile (OR, 3.5; 95% CI, 1.8 to 7.1), low maternal education (OR, 2.3; 95% CI, 1.1 to 4.7), regular daytime mouth breathing (OR, 7.4; 95% CI, 3.5 to 15.6), and a higher frequency of sore throats (OR, 17.6; 95% CI, 6.4 to 48.8) were independent risk factors for HS. Parental smoking and frequent infections were significantly but not independently associated with HS. The association of low maternal education and HS was higher in boys (OR, 4.4; 95% CI, 1.5 to 13.6; vs OR, 1.2; 95% CI, 0.4 to 3.6), while that of sore throats and HS was higher in girls (OR, 52.7; 95% CI, 6.0 to 460.2; vs OR, 13.3; 95% CI, 3.0 to 58.5). At follow-up, 39 of 80 eligible habitual snorers (48.8%) still snored regularly. Children who continued to snore differed significantly in maternal education, household smoking, snoring loudness, and prior ear, nose, throat surgery from those who had ceased to snore habitually.
Conclusions: Socioeconomic status, obesity, signs of nasal obstruction, and pharyngeal problems were independent risk factors for HS in these primary school children. The expression of HS varied considerably over time.

Habitual snoring (HS) [ie, snoring on most nights] is increasingly recognized as an important public health problem in adults, especially since a large population-based study^[1] revealed a high prevalence of HS (23%), and an association with daytime sleepiness independent of the frequency of obstructive sleep apnea (OSA) and cortical arousal. Thus, not only HS combined with OSA and daytime sleepiness (ie, OSA syndrome) or with multiple cortical arousals and daytime sleepiness (ie, upper airway resistance syndrome), but also primary snoring (ie, HS without OSA or multiple cortical arousals) appears to be linked to impaired daytime functioning in adults.

In contrast, HS seems to be less frequent in preschool children,^[2] school children,^[3,4,5] and adolescents,^[6] affecting approximately 1 in 10. Similar to adults, however, children with primary snoring and/or upper airway resistance syndrome also appear to exhibit impaired daytime functioning and may benefit from intervention. Studies demonstrated significant impairments in children with primary snoring and/or upper airway resistance syndrome^[7,8] and improvement in daytime functioning after surgical treatment for these conditions.^[8,9] As in adults, primary snoring and/or upper airway resistance syndrome, as well as OSA, may be important public health burdens in children. Thus, population-based, cross-sectional, and cohort studies are needed to further investigate risk factors and the natural history of HS. Identifying modifiable risk factors would give the opportunity for interventions by public health campaigns.

We recently performed a cross-sectional study^[5] on the prevalence of sleep-disordered breathing and its association with poor academic performance on a large cohort of primary school children. This included a questionnaire on most of the currently known risk factors for HS. In this report on that study, we determined the value of these factors in predicting HS and investigated its natural history. We focused on gender differences in associations between risk factors and HS, and speculated that gender differences are uncommon in this age group.

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