title: Definition of nocturnal gastroesophageal reflux for studies on respiratory diseases.
abstract: OBJECTIVE
  Nocturnal gastroesophageal reflux (nGER) has been associated with respiratory diseases. Our aim was to study a questionnaire method to identify nGER subjects with respiratory involvement in a general population.
  
  
  METHODS
  A subgroup of Icelandic participants in the European Community Respiratory Health Survey III (ECRHS III) reporting symptoms of nGER (n  =  48) as well as age and gender paired controls (n  =  42) were studied further by a structured interview, questionnaires, laryngeal fibrescopy, and exhaled breath condensate. A subgroup underwent 24-h oesophageal pH impedance (24-h MII-pH) measurements. Symptoms of nGER were assessed with a modified version of the reflux disease questionnaire (RDQ), where symptoms were divided into daytime and nocturnal. A report of nGER both at baseline and at follow-up was defined as persistent nGER.
  
  
  RESULTS
  Participants reporting persistent nGER had significantly more signs of laryngopharyngeal reflux according to the reflux finding score than those without nGER (Mean ± SD: 5.1 ± 2.3 vs. 3.9 ± 2.2, p  =  0.02). Of the 16 persistent nGER subjects that underwent 24-h MII-pH, 11 had abnormal gastroesophageal reflux, but none of three control subjects (69% vs. 0%). Pepsin was more commonly found in exhaled breath condensate in the nGER group (67% vs. 45%, p  =  0.04).
  
  
  CONCLUSIONS
  Participants with nGER symptoms at least once a month, reported on two occasions, had a high level of positive 24-h MII-pH measurements, laryngeal inflammation and pepsin in exhaled breath condensate. This nGER definition identified a representable group for studies on nGER and respiratory diseases in a general population.
authors.affiliation: a Faculty of Medicine, University of Iceland , Reykjavik , Iceland ;|b Department of Respiratory Medicine and Sleep , Landspitali University Hospital , Reykjavik , Iceland ;|c Department of Respiratory , Allergy and Sleep Research, Uppsala University , Uppsala , Sweden ;
authors.forename: Össur Ingi
authors.initials: ÖI
authors.lastname: Emilsson
authors.affiliation: a Faculty of Medicine, University of Iceland , Reykjavik , Iceland ;|b Department of Respiratory Medicine and Sleep , Landspitali University Hospital , Reykjavik , Iceland ;
authors.forename: Bryndís
authors.initials: B
authors.lastname: Benediktsdóttir
authors.affiliation: d Department of Clinical Biochemistry , Landspitali University Hospital , Reykjavik , Iceland ;
authors.forename: Ísleifur
authors.initials: Í
authors.lastname: Ólafsson
authors.affiliation: d Department of Clinical Biochemistry , Landspitali University Hospital , Reykjavik , Iceland ;
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Cook
authors.affiliation: a Faculty of Medicine, University of Iceland , Reykjavik , Iceland ;|e Department of Ear, Nose and Throat , Landspitali University Hospital , Reykjavik , Iceland ;
authors.forename: Sigurður
authors.initials: S
authors.lastname: Júlíusson
authors.affiliation: f Department of Otolaryngology and Head and Neck Surgery , Lund University , Lund , Sweden ;
authors.forename: Sören
authors.initials: S
authors.lastname: Berg
authors.affiliation: g Department of Surgical Sciences , Otorhinolaryngology and Head and Neck Surgery, Uppsala University , Uppsala , Sweden ;
authors.forename: Leif
authors.initials: L
authors.lastname: Nordang
authors.affiliation: a Faculty of Medicine, University of Iceland , Reykjavik , Iceland ;|h Department of Gastroenterology , Landspitali University Hospital , Reykjavik , Iceland.
authors.forename: Einar Stefán
authors.initials: ES
authors.lastname: Björnsson
authors.affiliation: h Department of Gastroenterology , Landspitali University Hospital , Reykjavik , Iceland.
authors.forename: Sunna
authors.initials: S
authors.lastname: Guðlaugsdóttir
authors.affiliation: h Department of Gastroenterology , Landspitali University Hospital , Reykjavik , Iceland.
authors.forename: Anna Soffía
authors.initials: AS
authors.lastname: Guðmundsdóttir
authors.affiliation: c Department of Respiratory , Allergy and Sleep Research, Uppsala University , Uppsala , Sweden ;
authors.forename: Christer
authors.initials: C
authors.lastname: Janson
authors.affiliation: a Faculty of Medicine, University of Iceland , Reykjavik , Iceland ;|b Department of Respiratory Medicine and Sleep , Landspitali University Hospital , Reykjavik , Iceland ;
authors.forename: Thorarinn
authors.initials: T
authors.lastname: Gislason
mesh_terms: D000328:Adult; D001944:Breath Tests; D050782:Esophageal pH Monitoring / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007055:Iceland / Q000453:epidemiology; D015994:Incidence; D007828:Laryngoscopy; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods*; D012140:Respiratory Tract Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D011795:Surveys and Questionnaires
keywords: Asthma; laryngopharyngeal reflux; nocturnal gastroesophageal reflux; pepsin; reflux disease questionnaire