title: The correlation among obesity, apnea-hypopnea index, and tonsil size in children.
abstract: BACKGROUND
  The correlation between obesity and severity of obstructive sleep apnea (OSA) is well established in adults, but data are inconsistent in children. We hypothesized that there is a significant correlation between the degree of obesity and the severity of OSA in children.
  
  
  METHODS
  We retrospectively reviewed records of weight, height, history, and polysomnography of all 1- to 15- year-old children referred to our sleep laboratory. Children with known anomalies and repeated polysomnography were excluded from this study. Obesity was defined as body mass index z score (BMI Z score) > 1.96. The correlation between BMI Z score and apnea-hypopnea index (AHI) was assessed. Possible confounding factors, ie, age, gender, and tonsil size, were adjusted by multiple linear regression.
  
  
  RESULTS
  Four hundred eighty-two children were included in this study. Obese children had a significantly higher AHI (median, 1.5; interquartile range [IQR], 0.2 to 7.0) than the AHI of nonobese children (median, 0.7; IQR, 0.0 to 2.5). BMI Z score was significantly correlated with log-transformed AHI (Ln[AHI]) [r = 0.156, p = 0.003]. BMI Z score and tonsil size were still correlated with Ln(AHI) even after adjusted for other confounding factors (p = 0.001).
  
  
  CONCLUSIONS
  Degree of obesity as measured by BMI Z score and tonsil size are significantly related to severity of OSA as reflected by the AHI, although the correlation is mild.
authors.affiliation: Department of Paediatrics, Kwong Wah Hospital, 25 Waterloo Road, Hong Kong SAR.
authors.forename: Yuen-yu
authors.initials: YY
authors.lastname: Lam
authors.forename: Eric Y T
authors.initials: EY
authors.lastname: Chan
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Ng
authors.forename: Chung-hong
authors.initials: CH
authors.lastname: Chan
authors.forename: Josephine M Y
authors.initials: JM
authors.lastname: Cheung
authors.forename: Shuk-yu
authors.initials: SY
authors.lastname: Leung
authors.forename: Pok-yu
authors.initials: PY
authors.lastname: Chow
authors.forename: Ka-li
authors.initials: KL
authors.lastname: Kwok
mesh_terms: D000234:Adenoids / Q000473:pathology; D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D005260:Female; D006723:Hong Kong; D006801:Humans; D006984:Hypertrophy / Q000453:epidemiology; D007223:Infant; D008297:Male; D009765:Obesity / Q000453:epidemiology*; D014066:Palatine Tonsil / Q000473:pathology*; D017286:Polysomnography; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000453:epidemiology*; D013223:Statistics as Topic