title: Characteristics of symptomatic reflux episodes on Acid suppressive therapy.
abstract: BACKGROUND
  Persistent symptoms on acid suppressive therapy are due to either acid or nonacid gastroesophageal reflux (GER) episodes or are not related to reflux.
  
  
  OBJECTIVE
  To compare physical and chemical characteristics of GER episodes associated with symptoms in patients on acid suppressive therapy.
  
  
  METHODS
  Patients with persistent symptoms on acid suppressive therapy underwent combined impedance-pH monitoring. Reflux episodes were classified as acid if nadir pH was <4.0, and nonacid if it remained at >/=4.0, separated into liquid-only or mixed (liquid-gas), and considered to reach the proximal esophagus if liquid was present 15 cm above the lower esophageal sphincter (LES). Reflux episodes were considered symptomatic if patients recorded a symptom within 5 min after the reflux episode. Risk factors of symptomatic reflux episodes were identified using multivariable generalized estimating equations (GEEs).
  
  
  RESULTS
  One hundred twenty patients (85 women, median age 54 yr, range 18-85 yr) recorded 3,547 reflux episodes (84.3% nonacid, 50.6% mixed), of which 468 (13.2%) were symptomatic. Based on multivariable GEE analysis with episode-level symptom status (symptomatic vs nonsymptomatic) as the outcome variable, reflux episode acidity was not significantly associated with symptoms (P= 0.40). Mixed reflux episodes were significantly associated with symptoms relative to liquid-only episodes (odds ratio [OR] 1.49, 95% confidence interval [CI] 1.19-1.87, P= 0.0005), as were reflux episodes reaching the proximal esophagus compared with those reaching the distal esophagus only (OR 1.28, 95% CI 1.06-1.55, P= 0.012).
  
  
  CONCLUSIONS
  The majority of reflux episodes on acid suppressive therapy are asymptomatic. Reflux episodes extending proximally and having a mixed (liquid-gas) composition are significantly associated with symptoms, irrespective of whether pH is acid (<4) or nonacid (>/=4).
authors.affiliation: Division of Gastroenterology and Hepatology, Medical University of South Carolina, Charleston, South Carolina, USA.
authors.forename: Radu
authors.initials: R
authors.lastname: Tutuian
authors.forename: Marcelo F
authors.initials: MF
authors.lastname: Vela
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Hill
authors.forename: Inder
authors.initials: I
authors.lastname: Mainie
authors.forename: Amit
authors.initials: A
authors.lastname: Agrawal
authors.forename: Donald O
authors.initials: DO
authors.lastname: Castell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004359:Drug Therapy, Combination; D005260:Female; D005745:Gastric Acidity Determination; D005764:Gastroesophageal Reflux / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology; D006635:Histamine H2 Antagonists / Q000627:therapeutic use; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D054328:Proton Pump Inhibitors / Q000627:therapeutic use*; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D006635:Histamine H2 Antagonists; D054328:Proton Pump Inhibitors