title: Los function and obesity: the impact of untreated obesity, weight loss, and chronic gastric balloon distension.
abstract: OBJECTIVE
  In obesity, many gastro-oesophageal reflux promoting factors are present. Weight reduction is advised to symptomatic overweight subjects. The aim of the present study was to investigate the influences of untreated obesity, weight loss, and chronic gastric balloon distension on the lower oesophageal sphincter (LOS) function.
  
  
  METHODS
  Patients entering a randomized, double-blind, sham-controlled study of balloon treatment, consisting of 4 months of either sham balloon or balloon treatment followed by 4 months of balloon treatment. Manometry and 24-hour pH measurements were performed at the start of the study and after 13 and 26 weeks.
  
  
  RESULTS
  Before treatment, LOS dysfunction was present in 7 of 32 patients (21.9%). Increased upright and supine reflux was present in 8 patients (25%). Sham treatment resulted in a weight loss of 9.7% with improved LOS function (a significant 0.6-cm increase in LOS length and a non-significant 2.6 mm Hg higher LOS pressure) and in a significantly decreased upright reflux (acid reflux time decreasing from 8.0 to 5.5% and number of meal-related and postprandial reflux episodes decreasing from 49 to 32). These improved values deteriorated after 4 months of balloon placement, with significantly increasing total, upright, and supine reflux to 7.5, 7.6, and 6.7% of the time, respectively, with oesophageal lesions after an overall 17.8% weight loss. Four months of balloon treatment induced a similar weight loss (9.9%) with significantly increased supine reflux from 1.6 to 6.7% of the time. After a second 4-month balloon period and an overall 13.8% weight loss, LOS and reflux values returned towards baseline values. A comparison of both groups demonstrated the adverse effects of balloon positioning after a period of substantial sham-induced weight loss.
  
  
  CONCLUSIONS
  Impaired LOS function and increased gastro-oesophageal reflux were observed in one quarter of the untreated obese subjects. Weight loss ameliorated manometry and pH values, but subsequent balloon positioning tended to counteract these beneficial changes. In patients on balloon treatment from the start, adverse effects seemed to wear off with prolonged treatment.
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands. e.mathus-vliegen@amc.uva.nl
authors.forename: E M H
authors.initials: EM
authors.lastname: Mathus-Vliegen
authors.forename: M
authors.initials: M
authors.lastname: van Weeren
authors.forename: P V
authors.initials: PV
authors.lastname: van Eerten
mesh_terms: D004311:Double-Blind Method; D016099:Endoscopy, Gastrointestinal; D015905:Gastric Balloon / Q000009:adverse effects*; D005764:Gastroesophageal Reflux / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008365:Manometry; D009765:Obesity / Q000150:complications* / Q000628:therapy*; D015431:Weight Loss / Q000502:physiology