Diagnostic interpretation of extended pH monitoring: is there a single best method?

Area of Science:

• Pediatric Gastroenterology
• Diagnostic Accuracy Studies

Background:

• Gastroesophageal reflux (GER) diagnosis in infants often relies on pH monitoring.
• Traditional metrics like the reflux index (RI) may have limitations in identifying pathologic GER, especially in formula-fed infants.

Purpose of the Study:

• To compare the diagnostic performance of RI, Euler and Byrne score (EBS), and area under the curve (AUC) at pH < 4.0 for pathologic GER in infants.
• To establish new, more accurate cutoff values for these metrics in formula-fed infants.

Main Methods:

• Prospective investigation using extended pH monitoring (EPM) in 117 infants with GER symptoms.
• Infants classified using RI (≥5%), EBS (≥50), or AUC (pH < 4.0 or ≤21.3).
• Receiver operating characteristic (ROC) curve analysis used to determine new cutoffs and assess specificity and sensitivity.

Main Results:

• Pathologic GER prevalence varied: RI (23%), EBS (56%), AUC (57%).
• Specificities were high for all: RI (97.8%), EBS (100.0%), AUC (100.0%).
• Sensitivities were also high: RI (93.0%), EBS (91.5%), AUC (94.4%).
• A revised RI cutoff of 2.1% was identified via ROC analysis to enhance diagnostic accuracy.

Conclusions:

• Traditional RI alone may underestimate pathologic GER in formula-fed infants.
• Revised RI cutoff values and AUC analysis using computerized pH tracings significantly enhance diagnostic accuracy for GER.