title: Testing the association between gastroesophageal reflux and apnea in infants.
abstract: BACKGROUND
  There is controversy regarding the association between gastroesophageal reflux and apnea. The controversy is further confused by the variety of ways reflux is detected, the varying methods of data analysis and the heterogeneity of subjects studied.
  
  
  OBJECTIVE
  To determine if apnea is associated with reflux and to determine whether the association differs with acid or non acid reflux.
  
  
  METHODS
  We prospectively evaluated infants with apparent life-threatening events or apnea by simultaneous pneumography, esophageal pH and multichannel intraluminal impedance monitoring. Apneic events and reflux frequency, duration, acidity and height were recorded. Apneic events were considered to be temporally linked to gastroesophageal reflux when they occurred during a gastroesophageal reflux episode or within 5 minutes after clearance of the refluxate. Data described with frequency tables, scatterplots and time series graphs were analyzed by regression analysis and chi testing.
  
  
  RESULTS
  Twenty-five infants (10 males) aged 1 to 19 months were studied for up to 24 hours. Of 527 total apneic episodes, only 80 (15.2%) were temporally linked with gastroesophageal reflux: 37 (7.0%) with acid reflux and 43 (8.2%) with non-acid reflux. Scatterplots revealed no significant correlation between apnea and frequency or duration of reflux episodes. Individual chi analyses within subjects found limited associations between reflux and apnea. Regression analyses showed a significant association between apnea and reflux in 4 of 25 subjects.
  
  
  CONCLUSIONS
  We found little evidence for an association between apnea and total reflux, acid reflux or non-acid reflux. There was no difference between acid gastroesophageal reflux and non-acid gastroesophageal reflux in the frequency association with apnea. Either a chi statistic for each subject or R value computed from a lagged regression model for each subject can be used as an index of association in patient evaluation.
authors.affiliation: The Center for Advanced Research in Neuromuscular Gastrointestinal Disorders (CARING), Division of Pediatric Gastroenterology, Columbus Children's Hospital, The Ohio State University School of Medicine 43205, USA. mousah@pediatrics.ohio-state.edu
authors.forename: Hayat
authors.initials: H
authors.lastname: Mousa
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Woodley
authors.forename: Melissa
authors.initials: M
authors.lastname: Metheney
authors.forename: John
authors.initials: J
authors.lastname: Hayes
mesh_terms: D001049:Apnea / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D017097:Electric Impedance; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D008297:Male; D011446:Prospective Studies; D013997:Time Factors