title: The association between secondhand smoke and sleep-disordered breathing in children: a systematic review.
abstract: OBJECTIVE
  To systematically review existing literature on the association between secondhand smoke and sleep-disordered breathing in children.
  
  
  METHODS
  PubMed, Embase, Cochrane CENTRAL, Web of Science, and Scopus.
  
  
  METHODS
  Inclusion criteria included English-language papers containing original human data, with seven or more subjects and age <18 years. Data were systematically collected on study design, patient demographics, clinical characteristics/outcomes, and level of evidence. Two investigators independently reviewed all manuscripts.
  
  
  RESULTS
  The initial search yielded 72 abstracts; 18 articles were ultimately included with a total study population of 47,462 patients. Fifteen (83%) articles found a statistically significant association between secondhand smoke and sleep-disordered breathing. All were case-control studies. Quality of articles based on the Newcastle-Ottawa scale averaged 5.8/9 stars. Secondhand smoke was characterized by serum cotinine testing in only two (11%) studies. Sleep-disordered breathing was quantified by polysomnography in only four (22%) of the studies and only one (6%) classified subject using polysomnography exclusively. Habitual snoring was the most common form of sleep-disordered breathing studied in 14/18 (78%) studies, whereas obstructive sleep apnea was reported in one (6%) study and sleep-related hypoxia in another (6%) study.
  
  
  CONCLUSIONS
  Although the majority of studies included in this review found a significant association between secondhand smoke and sleep-disordered breathing, all of them were evidence level 3b, for an overall grade of B (Oxford Centre for Evidence-based Medicine). Further higher-quality studies should be performed in the future to better evaluate the relationship between second- smoke and sleep-disordered breathing in children.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Sebastian M
authors.initials: SM
authors.lastname: Jara
authors.forename: James R
authors.initials: JR
authors.lastname: Benke
authors.forename: Sandra Y
authors.initials: SY
authors.lastname: Lin
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Ishman
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D017286:Polysomnography; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000209:etiology*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000209:etiology; D012913:Snoring / Q000175:diagnosis / Q000209:etiology; D013223:Statistics as Topic; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution
keywords: Secondhand smoke; obstructive sleep apnea; pediatric; sleep-disordered breathing; snoring; systematic review