title: Craniofacial and upper airway morphology in pediatric sleep-disordered breathing: Systematic review and meta-analysis.
abstract: BACKGROUND
  Pediatric sleep-disordered breathing is a continuum, with primary snoring at one end, and complete upper airway obstruction, hypoxemia, and obstructive hypoventilation at the other. The latter gives rise to obstructive sleep apnea. An important predisposing factor in the development and progression of pediatric sleep-disordered breathing might be craniofacial disharmony. The purpose of this systematic review and meta-analysis was to elucidate the association between craniofacial disharmony and pediatric sleep-disordered breathing.
  
  
  METHODS
  Citations to potentially relevant published trials were located by searching PubMed, Embase, Scopus, and the Cochrane Central Register of Controlled Trials. The MetaRegister of controlled trials database was also searched to identify potentially relevant unpublished trials. Additionally, hand-searching, Google Scholar searches, and contact with experts in the area were undertaken to identify potentially relevant published and unpublished studies. Inclusion criteria were (1) randomized controlled trials, case-control trials, or cohort studies with controls; (2) studies in nonsyndromic children 0 to 18 years of age with a diagnosis of sleep-disordered breathing or obstructive sleep apnea by either a sleep disorders unit, screening questionnaire, or polysomnography; and (3) principal outcome measures of craniofacial or upper airway dimensions or proportions with various modalities of imaging for the craniofacial and neck regions. The quality of the studies selected was evaluated by assessing their methodologies. Treatment effects were combined by meta-analysis with the random-effects method.
  
  
  RESULTS
  Children with obstructive sleep apnea and primary snoring show increased weighted mean differences in the ANB angle of 1.64° (P <0.0001) and 1.54° (P <0.00001), respectively, compared with the controls. An increased ANB angle was primarily due to a decreased SNB angle in children with primary snoring by 1.4° (P = 0.02). Children with obstructive sleep apnea had a distance from the posterior nasal spine to the nearest adenoid tissue measured along the PNS-basion line reduced by 4.17 mm (weighted mean difference) (P <0.00001) and a distance from the posterior nasal spine to the nearest adenoid tissue measured along the line perpendicular to the sella-basion line reduced by 3.12 mm (weighted mean difference) (P <0.0001) compared with the controls.
  
  
  CONCLUSIONS
  There is statistical support for an association between craniofacial disharmony and pediatric sleep-disordered breathing. However, an increased ANB angle of less than 2° in children with obstructive sleep apnea and primary snoring, compared with the controls, could be regarded as having marginal clinical significance. Therefore, evidence for a direct causal relationship between craniofacial structure and pediatric sleep-disordered breathing is unsupported by this meta-analysis. There is strong support for reduced upper airway width in children with obstructive sleep apnea. Larger well-controlled trials are required to address the relationship of craniofacial and upper airway morphology to pediatric sleep-disordered breathing in all 3 dimensions.
authors.affiliation: Postgraduate student, Orthodontic Unit, University of Adelaide, Adelaide, Australia. vandykatyal@gmail.com
authors.forename: Vandana
authors.initials: V
authors.lastname: Katyal
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Pamula
authors.forename: A James
authors.initials: AJ
authors.lastname: Martin
authors.forename: Cathal N
authors.initials: CN
authors.lastname: Daynes
authors.forename: J Declan
authors.initials: JD
authors.lastname: Kennedy
authors.forename: Wayne J
authors.initials: WJ
authors.lastname: Sampson
mesh_terms: D000234:Adenoids / Q000473:pathology; D000293:Adolescent; D002508:Cephalometry; D002648:Child; D002675:Child, Preschool; D006801:Humans; D006984:Hypertrophy; D007223:Infant; D007830:Larynx / Q000473:pathology; D016013:Likelihood Functions; D009666:Nose / Q000473:pathology; D010614:Pharynx / Q000473:pathology*; D012891:Sleep Apnea Syndromes / Q000473:pathology*; D020181:Sleep Apnea, Obstructive / Q000473:pathology