From April 2008 to January 2010, 70 children with suspicion of GER (ages between two-seventeen) complaining of heartburn, abdominal pain, recurrent regurgitation, vomiting, failure to thrive, respiratory symptoms such as recurrent respiratory infection, pharyngitis/tonsilitis, otitis, croup, bronchiolitis, persistent cough, wheezing (non related atopy) seen at the Pediatric Outpatient Clinic, Duzce University Medical School Hospital, Duzce, Turkey, were enrolled in the study prospectively. All patients were questioned by the presence of chronic diseases. Demographic and clinical data including patient age, sex, growth parameters such as length and weight were recorded.
Examined group of 70 patients was divided into 3 subgroups of patients having gastrointestinal complaints, respiratory complaints, and mixed symptoms (gastrointestinal and respiratory symptoms both). The diagnostic method for GER detection was 24 hour esophageal pH-metry
24-hour pH metry
The pH metry analysis was performed by an Orion II Ambulatory pH-metry (Medical Measurement Systems Company, Enschede, The Netherlands). The probe was a 2.1-mm outer diameter two sensors placed 5 cm apart, single use pH catheter with a reference electrode (Synectics Medical MMS). Prior to the each test, the electrodes were calibrated in buffer solutions (Reagecon Biomedical, Ireland) at pH 7 and pH 1. This method required placing the pH probe distally until a clearly acidic pH (1.5-2.5) was achieved and then slowly withdrawing the probe until the pH rose to approximately 4.0. At that point, the pH probe was most likely to be in the esophagogastric junction. The probe was then withdrawn to 3-4 cm above the level and fixed at that point. The electrode position was always confirmed by a plain chest radiograph. Before placement of the probe the children had to be fasting for at least 6 hours.
Patients received regular feeds. Daily activities and feeding times were recorded during 24 hours.
Data were analyzed by the MMS investigation and diagnostic software v8.7, for Windows.
All 24 hr pH-metry recordings were manually analyzed and all data underwent visual validation. The DeMeester score was used to define pathological GER  recorded by the distal sensor. The following parameters were compared:
Number of reflux episodes
Number of reflux episodes longer than 5 minutes in 24 hours
Longest episode of reflux (in minutes)
Fraction of time with pH lower than 4 was considered abnormal if greater than 5%.
Reflux index (number of refluxes per hour).
A diagnosis of GER was established when reflux index was greater than >4, or DeMeester score was higher than 14.7, or pathological reflux was considered as at least 1 reflux episode with a pH below 4 in the proximal sensor.
Frequency counts and cross-tabs were used to describe nominal variables. Chi square test was used for the analyses of categorical variables. Man Whitney-U test was used for analyses of numeric variables. Kruskal Wallis H was used for analyzing multiple groups and Boferroni adjusted Man Whitney-U test was used for multiple comparisons. Statistical analyses were carried out using the SPSS 10.0 for Windows. P values < 0.05 were considered significant.
The study protocol was approved by the Ethics Committee of Duzce University Hospital. All subjects gave written informed consent.