title: Comparison of wireless 48-h (Bravo) versus traditional ambulatory 24-h esophageal pH monitoring.
abstract: OBJECTIVE
  To compare wireless with catheter-based esophageal pH recordings.
  
  
  METHODS
  Forty-five patients with symptoms suggestive of gastroesophageal reflux disease and 47 healthy volunteers were investigated in a university-affiliated hospital; 48-h wireless esophageal pH recording was performed. During the first 24 h, simultaneous traditional pH recording by catheter was undertaken. Nine of the volunteers underwent repeated measurements with both techniques. Outcome measures were feasibility, agreement, concordance of diagnostic yield, reproducibility, and subjective symptoms.
  
  
  RESULTS
  Subjective parameters were less affected when using the wireless technique alone (p<0.05). On using the wireless technique, esophageal acid exposure was underestimated approximately by half compared with traditional recording (p<0.05). Although pH data obtained with the two techniques were correlated (r(2)=0.66, p<0.001), the range between limits of agreement was wide (-3.7 to 10.0 percentage units of total time pH <4). Coefficients of variation for repeated measurements were 60.1+/-26.3% for catheter recordings, and 66.0+/-47.3 for wireless recordings on day 1 (NS). Concordance of diagnostic yield was 81.5% with all subjects included.
  
  
  CONCLUSIONS
  Forty-eight-hour wireless Bravo pH monitoring is feasible but consistently underestimates esophageal acid exposure compared to the conventional technique. Although there is a significant correlation between the two techniques for pH recordings, the wide range in limits of agreement and the large coefficient of variation with both techniques suggest that the two methods are not immediately interchangeable for use in clinical practice.
authors.affiliation: Department of Surgery, Center of Gastrointestinal Disease, Ersta Hospital, Stockholm, Sweden. bengt.hakanson@erstadiakoni.se
authors.forename: Bengt S
authors.initials: BS
authors.lastname: Håkanson
authors.forename: Per
authors.initials: P
authors.lastname: Berggren
authors.forename: Staffan
authors.initials: S
authors.lastname: Granqvist
authors.forename: Olle
authors.initials: O
authors.lastname: Ljungqvist
authors.forename: Anders
authors.initials: A
authors.lastname: Thorell
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D050782:Esophageal pH Monitoring / Q000295:instrumentation*; D004945:Esophagoscopy; D005240:Feasibility Studies; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric