Analyzing the Area Under the Curve of Pharyngeal pH Probes in the Diagnosis of Reflux Disease.

OBJECTIVES: To analyze the area under the curve (AUC) from 24-hour pharyngeal pH probes and evaluate this parameter as a predictor of disease severity for laryngopharyngeal reflux. METHODS: Eighty patients met inclusion criteria of a completed 24-hour pharyngeal pH probe and Reflux Symptom Index (RSI) questionnaire. The AUC was calculated below a pH threshold of 5.5 using the trapezoidal rule. The RSI and RYAN scores were correlated with AUC values, and nonparametric tests were used for comparisons. RESULTS: The median AUC value was 18 007 pH-seconds with an interquartile range (IQR) of 63 156, the median RSI score was 21 (IQR = 16), and the median RYAN score was 15.3 (IQR = 78). There was a Spearman's correlation of .36 between the RSI scores and AUC values ( P = .001) and a moderate correlation between AUC values and RYAN scores (0.58, P < .001). An insignificant correlation of .19 between RYAN scores and RSI scores was observed ( P = .09). CONCLUSIONS: The AUC may be a useful objective value in establishing the diagnosis of laryngopharyngeal reflux. Prospective studies with larger patient populations are necessary to validate these findings and determine standardized thresholds for symptomatic patients.