[A comparison of pH<4 and pH<5 as thresholds for 24-hour pH monitoring in the diagnosis of laryngopharyngeal reflux].

Objective: To evaluate the consistency between 24-hour pH monitoring, reflux symptom index(RSI) and reflux finding score(RFS) when using pH<4 or pH<5 as threshold for 24-hour pH monitoring in the diagnosis of laryngopharyngeal reflux. Methods: Patients who presented with suspicious laryngopharyngeal reflux between February 2014 and December 2015 were included in this study. pH<4 and pH<5 reflux episodes, RSI and RFS were collected. The consistency between 24-hour pH monitoring and scale results were analyzed when pH<4 or pH<5 as threshold respectively. The sensitivity and specificity of 24-hour pH monitoring were calculated separately. Results: Median number(M[P25, P75, P95]) of reflux events were 0 [0, 3.0, 5.5] when using pH<4 as pathological threshold and 0 [0, 4.0, and 8.5] using pH<5 as pathological threshold. Laryngopharyngeal reflux was determined in 34.5% patients depending on 24-hour pH monitoring when pH<4 was used as threshold, chi-square revealed medium consistency (κ=0.483) between pH monitoring and scale result. If pH<5 was used as threshold, 41.8% patients were detected with laryngopharyngeal reflux, and the consistency of pH monitoring and scale result was medium(κ=0.540). With RSI and RFS for reference, the sensitivity and specificity of 24-hour pH monitoring were 54.7% and 93.4% respectively when pH<4 was used as threshold. If pH<5 was used as threshold, the sensitivity and specificity of 24-hour pH monitoring were 65.6% and 91.3% respectively. Conclusions: Compared with pH<4 as pathological threshold, the consistency of pH monitoring and scale results was a little better using pH<5 as pathological threshold.