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

Abstract

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. 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. 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). 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.