title: Seasonal variability in paediatric obstructive sleep apnoea.
abstract: BACKGROUND
  Allergy and respiratory viral infection may contribute to the pathogenesis of sleep disordered breathing (SDB) through promoting adenotonsillar growth. We investigated the seasonal variation of SDB in children by analysing the change in the obstructive apnoea hypopnoea index (OAHI) throughout the year.
  
  
  METHODS
  257 3-12-year-old children referred for assessment of SDB underwent overnight polysomnography (PSG).
  
  
  RESULTS
  Mean seasonal OAHI was significantly higher in winter (5.1±0.8 events/h) and spring (4.6±0.9 events/h) compared with autumn (2.4±0.8 events/h; p<0.01 and p<0.05, respectively) and summer (2.0±0.5 events/h; p<0.05 for both). There were no differences in OAHI between summer and the other seasons or between winter and spring.
  
  
  CONCLUSIONS
  We identified more severe obstructive sleep apnoea in clinically referred children during winter and spring and suggest that inflammation from respiratory viruses may contribute to adenotonsillar hypertrophy, worsening airway obstruction. Clinicians should take season into account when interpreting PSG results.
authors.affiliation: The Ritchie Centre, Level 5, Monash Institute of Medical Research, Monash Medical Centre, 246 Clayton Road, Clayton, VIC 3168, Australia. lisa.walter@monash.edu
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Walter
authors.forename: Lauren C
authors.initials: LC
authors.lastname: Nisbet
authors.forename: Gillian M
authors.initials: GM
authors.lastname: Nixon
authors.forename: Margot J
authors.initials: MJ
authors.lastname: Davey
authors.forename: Vicki
authors.initials: V
authors.lastname: Anderson
authors.forename: John
authors.initials: J
authors.lastname: Trinder
authors.forename: Adrian M
authors.initials: AM
authors.lastname: Walker
authors.forename: Rosemary S C
authors.initials: RS
authors.lastname: Horne
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography; D012621:Seasons; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*