title: Accuracy of the water-siphon test associated to barium study in a high prevalence gastro-oesophageal reflux disease population: a novel statistical approach.
abstract: OBJECTIVE
  Gastro-oesophageal reflux disease (GORD) is 'a condition which develops when the reflux of gastric content causes troublesome symptoms or complications'. Instrumental diagnostic tests generally used for GORD are 24-hour pH-metry and upper gastrointestinal (GI) endoscopy but barium study associated with provocative manoeuvres such as the water-siphon test (WST), has also been used for GORD. The aim of this paper was to estimate the accuracy of several tests in patients with GORD in a tertiary care setting, focusing on WST, which is rapid and non-invasive, simple to perform and well-tolerated by patients.
  
  
  METHODS
  A total of 172 consecutive patients, symptomatic for reflux referred to a tertiary medical centre, were considered and data regarding the WST, 24-hour pH-metry, upper GI endoscopy with histology were analysed using latent class analysis, a multivariable statistical method for estimating the accuracy of tests when a gold standard is not available.
  
  
  RESULTS
  The overall proportion of GORD in the sample was estimated at 0.664 [95% confidence interval (CI) = (0.589; 0.731)]. WST proved to be the most sensitive [Se = 0.886; 95% CI = (0.688; 1.000)] compared with pH-metry [Se = 0.620; 95% CI = (0.493; 0.745)] and endoscopy with histology [Se = 0.534; 95% CI = (0.273; 0.789)]. It was less specific [Sp = 0.537; 95% CI = (0.003; 1.000)] than pH-metry [Sp = 0.547; 95% CI = (0.281; 0.813)], and even less than endoscopy with histology [Sp = 0.862; 95% CI = (0.495; 1.00)]. Positive predictive values were estimated at 0.792 [95% CI = (0.721; 0.862)] for WST, 0.731 [95% CI = (0.643; 0.819)] for pH-metry and 0.886 [95% CI = (0.811; 0.961)] for endoscopy with histology. Negative predictive values were estimated at 0.707 [95% CI = (0.573; 0.841)] for WST, 0.422 [95% CI = (0.310; 0.534)] for pH-metry and 0.484 [95% CI = (0.387; 0.581)] for endoscopy with histology.
  
  
  CONCLUSIONS
  Water-siphon test might possibly be useful in patients with suspected GORD because it is highly sensitive and predictive. A positive outcome of the WST associated with a barium study can certainly justify upper GI endoscopy and support any pharmacological treatment of GORD.
authors.affiliation: Clinical Professor of Surgery, Dipartimento di Chirurgia Generale, Urgenza e Trapianti d'Organo, Universita di Palermo, Palermo, Italy. efiorentino@unipa.it
authors.forename: Eugenio
authors.initials: E
authors.lastname: Fiorentino
authors.forename: Domenica
authors.initials: D
authors.lastname: Matranga
authors.forename: Gianni
authors.initials: G
authors.lastname: Pantuso
authors.forename: Daniela
authors.initials: D
authors.lastname: Cabibi
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Bonventre
authors.forename: Filippo
authors.initials: F
authors.lastname: Barbiera
mesh_terms: D000328:Adult; D000368:Aged; D001466:Barium Sulfate; D003627:Data Interpretation, Statistical; D003938:Diagnostic Techniques, Digestive System / Q000592:standards*; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D006801:Humans; D008875:Middle Aged; D015203:Reproducibility of Results; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water; D001466:Barium Sulfate