title: The effect of seasonality on sleep-disordered breathing severity in children.
abstract: OBJECTIVE
  Sleep-disordered breathing (SDB) is a common disorder associated with substantial morbidity that occurs in otherwise healthy children. Atopy, asthma, and viral upper respiratory tract infections are known risk factors for pediatric SDB that exhibit seasonal variability. The aim of our study was to investigate the effect of seasonality on SDB severity in children and adolescents referred for polysomnographic evaluation for suspected SDB and to examine the effect of atopy/asthma on this variability.
  
  
  METHODS
  The medical records of all children and adolescents referred for a polysomnography (PSG) for suspected SDB between 2008 and 2010 were retrospectively assessed for seasonal patterns. The effect of atopy/asthma, age, and obesity on seasonal variability was investigated.
  
  
  RESULTS
  A total of 2178 children and adolescents (65% boys) were included. The mean age of the cohort was 4.9±3.5 years (range, 3 months-18 years). Eighteen percent of patients had a history of asthma/atopy. The mean obstructive apnea-hypopnea index (OAHI) in the winter was significantly higher compared to the summer (9.1±9.6 vs. 7.5±7.0; P=.01; Cohen d=0.19), particularly in children younger than the age of 5 years (10.2±10.5 vs. 7.9±7.3; P=.008; Cohen d=0.25). Asthma/atopy had no significant effect on seasonal variability.
  
  
  CONCLUSIONS
  SDB severity alters in a season-dependent manner in children and adolescents referred for polysomnographic evaluation for suspected SDB. These alterations are more prominent in children younger than the age of 5 years. The presence of asthma/atopy does not contribute to this seasonal variability. These findings suggest that viral respiratory infections are most likely the major contributor for the seasonal variability observed in pediatric SDB; additionally, the time of the year when a child is evaluated for suspected SDB may affect the clinical management and outcome in borderline cases.
authors.affiliation: Pediatric Sleep Center, Dana Children's Hospital, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Greenfeld
authors.forename: Yakov
authors.initials: Y
authors.lastname: Sivan
authors.forename: Riva
authors.initials: R
authors.lastname: Tauman
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000150:complications; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000150:complications; D007223:Infant; D008297:Male; D009765:Obesity / Q000150:complications; D017286:Polysomnography; D012189:Retrospective Studies; D012621:Seasons; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000503:physiopathology*
keywords: Asthma; Atopy; Children; Obstructive sleep apnea; Seasonality; Sleep disordered breathing