title: Disagreement between symptom-reflux association analysis parameters in pediatric gastroesophageal reflux disease investigation.
abstract: OBJECTIVE
  To assess the agreement within 3 commonly used symptom-reflux association analysis (SAA) parameters investigating gastroesophageal reflux disease (GERD) in infants.
  
  
  METHODS
  Twenty three infants with suspected GERD were included in this study. Symptom index (SI), Symptom sensitivity index (SSI) and symptom association probability (SAP) related to cough and irritability were calculated after 24 h combined pH/multiple intraluminal impedance (MII) monitoring. Through defined cut-off values, SI, SSI and SAP values are differentiated in normal and abnormal, whereas abnormal values point towards gastroesophageal reflux (GER) as the origin of symptoms. We analyzed the correlation and the concordance of the diagnostic classification of these 3 SAA parameters.
  
  
  RESULTS
  Evaluating the GER-irritability association, SI, SSI and SAP showed non-identical classification of normal and abnormal cases in 39.2% of the infants. When irritability was taken as a symptom, there was only a poor inter-parameter association between SI and SSI, and between SI and SAP (Kendall's tau b = 0.37, P < 0.05; Kendall's tau b = 0.36, P < 0.05, respectively). Evaluating the GER-cough association, SI, SSI and SAP showed non-identical classification of normal and abnormal cases in 52.2% of the patients. When cough was taken as a symptom, only SI and SSI showed a poor inter-parameter association (Kendall's tau b = 0.33, P < 0.05).
  
  
  CONCLUSIONS
  In infants investigated for suspected GERD with pH/MII-monitoring, SI, SSI and SAP showed a poor inter-parameter association and important disagreements in diagnostic classification. These limitations must be taken into consideration when interpreting the results of SAA in infants.
authors.affiliation: Division of Gastroenterology, Departement of Pediatrics, Hospital of Fribourg, CH-1708 Fribourg, Switzerland. samuel_luethold@bluewin.ch
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Lüthold
authors.forename: Mascha K
authors.initials: MK
authors.lastname: Rochat
authors.forename: Peter
authors.initials: P
authors.lastname: Bähler
mesh_terms: D001466:Barium Sulfate; D001706:Biopsy; D003287:Contrast Media; D003371:Cough / Q000209:etiology*; D016145:Endoscopy, Digestive System; D050782:Esophageal pH Monitoring; D005764:Gastroesophageal Reflux / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy / Q000523:psychology; D006801:Humans; D007223:Infant; D018730:Infant Behavior; D007231:Infant, Newborn; D007508:Irritable Mood; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D003287:Contrast Media; D001466:Barium Sulfate