Inter- and intraobserver agreement in 24-hour combined multiple intraluminal impedance and pH measurement in children.

OBJECTIVES: Assessment of intra- and interobserver agreement in multiple intraluminal impedance (MII) measurement between investigators from different institutions. METHODS: Twenty-four 18- to 24-hour MII tracings were randomly chosen from 4 different institutions (6 per center). Software-aided automatic analysis was performed. Each result was validated by 2 independent investigators from the 4 different centers (4 investigator combinations). For intraobserver agreement, 6 measurements were analyzed twice by the same investigator. Agreement between investigators was calculated using the Cohen kappa coefficient. RESULTS: Interobserver agreement: 13 measurements showed a perfect agreement (kappa > 0.8); 9 had a substantial (kappa 0.61-0.8), 1 a moderate (kappa coefficient 0.41 to 0.6), and 1 a fair agreement (kappa coefficient 0.11-0.4). Median kappa value was 0.83. Intraobserver agreement: 5 tracings showed perfect and 1 showed a substantial agreement. The median kappa value was 0.88. CONCLUSIONS: Most measurements showed substantial to perfect intra- and interobserver agreement. Still, we found a few outliers presumably caused by poorer signal quality in some tracings rather than being observer dependent. An improvement of analysis results may be achieved by using a standard analysis protocol, a standardized method for judging tracing quality, better training options for method users, and more interaction between investigators from different institutions.

Detection of gastroesophageal reflux in children using combined multichannel intraluminal impedance and pH measurement: data from the German Pediatric Impedance Group.

OBJECTIVE: To validate the use of combined multichannel intraluminal impedance (MII)-pH (MII-pH) monitoring for detecting gastroesophageal reflux (GER) in children in daily clinical practice. STUDY DESIGN: The patients were divided into 3 symptom groups based on the main indication for the procedure. MII-pH monitoring was performed in 700 children presenting with symptoms suggestive of GER, including 329 children with pulmonary symptoms, 325 with gastrointestinal symptoms, and 46 with neurologic symptoms. The MII-pH results were compared with pH monitoring alone, and retrograde bolus movements, symptom index, and symptom association probability were compared. RESULTS: Overall, 270 measurements were abnormal: 101 (37%) showed abnormal MII-pH study, 49 (18%) showed only pathological pH measurements and 120 measurements (45%) had an abnormal MII recording only. Extraintestinal symptoms of GER were seen more often in younger children and were more often related to a normal pH study but an abnormal MII study. Infants had a significantly higher number of retrograde bolus movements than older children. Symptom index and symptom association probability showed moderate agreement (Cohen kappa, 0.54). CONCLUSIONS: From this large systematically standardized data collection of MII-pH measurements in children, we conclude that 45% of the patients with abnormal GER would not have been recognized by 24-hour pH measurement alone. Our findings confirm that MII-pH is superior to pH monitoring alone in detecting GER.