title: Waist to hip ratio is a better predictor of esophageal acid exposure than body mass index.
abstract: BACKGROUND
  Obesity and gastroesophageal reflux disease (GERD) are major health problems showing an inconstant relationship in the literature. Therefore, anthropometric parameters which are predictive and can simply be assessed at first patient presentation may lead to a better patient selection for ambulatory reflux monitoring. We aimed to examine the association of body mass index (BMI) and waist to hip ratio (WHR) with gastroesophageal reflux activity during 24 hour-pH-impedance monitoring.
  
  
  METHODS
  Seven hundred and seventy-one patients with GERD symptoms underwent 24 hour-pH-impedance monitoring and high resolution manometry off proton pump inhibitors. Patients with known primary motility disorders of the esophagus and pre-existing endoscopic or operative procedure on esophagus or stomach were excluded from the study. Reflux parameters and anthropometric and demographic data from our prospectively gathered database were analyzed. We performed univariate and multivariate regression analysis to evaluate the associations of BMI and WHR with reflux parameters measured with 24 hour-pH-impedance monitoring.
  
  
  RESULTS
  WHR showed a significantly stronger association with esophageal acid exposure than BMI (P<.001). Our data show that 6.9% of the percentage of endoluminal pH<4 in the distal esophagus is attributable to WHR. Furthermore, an association of WHR with impaired esophageal acid clearance was observed. Additionally, we observed an inverse relationship between lower esophageal sphincter integrity (P=.05) and esophageal acid exposure.
  
  
  CONCLUSIONS
  WHR is a better predictor for esophageal acid exposure than BMI. Biomechanical and metabolic mechanisms of central fat distribution may influence reflux parameters in 24 hour pH impedance monitoring, which may affect patient selection for ambulatory reflux monitoring.
authors.affiliation: Department of Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: C
authors.identifier: http://orcid.org/0000-0002-5192-8330
authors.initials: C
authors.lastname: Ringhofer
authors.affiliation: Department of Visceral Medicine and Surgery, University of Bern, Bern, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Lenglinger
authors.affiliation: Department of Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Riegler
authors.affiliation: Department of Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: I
authors.initials: I
authors.lastname: Kristo
authors.affiliation: Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Kainz
authors.affiliation: Department of Surgery, Medical University of Vienna, Vienna, Austria.
authors.forename: S F
authors.initials: SF
authors.lastname: Schoppmann
mesh_terms: D000328:Adult; D015992:Body Mass Index; D050782:Esophageal pH Monitoring / Q000379:methods / Q000592:standards*; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods / Q000592:standards; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D049629:Waist-Hip Ratio / Q000379:methods / Q000592:standards*
keywords: body mass index; gastroesophageal reflux disease; reflux monitoring; waist to hip ratio