Symptom reports are not reliable during ambulatory reflux monitoring

Patient reporting of symptom events during ambulatory reflux monitoring is commonly performed with little data regarding its accuracy. We employed a novel time-synchronized ambulatory audio recording of symptom events simultaneously with prolonged pH/impedance monitoring to assess temporal accuracy of patient-reported symptoms.

An acoustic monitoring system was employed to detect cough events via tracheal and chest wall sounds and it was temporally synchronized with an ambulatory impedance/pH monitoring system. Patients were instructed to record their symptoms in the usual manner. Six separate observers independently listened to the 24-h audio recordings and logged the exact timing of each cough event. Patients were blinded to study design and the audio reviewers were blinded to their own reports and those of patients and other reviewers. Concurrence of audio recordings and patient-reported symptoms were tested for three separate time thresholds: 1, 2, and 5 min.

The median (interquartile range (IQR)) number of cough events by audio detection was significantly (P<0.001) higher than those reported by patients: 216 (90-275) and 34 (22-60), respectively. There was significantly (P<0.001) higher agreement among the audio recording listeners (substantial to almost perfect agreement; kappa=0.77-0.82) than between the audio recording and patient-reported symptoms (slight to fair agreement; kappa=0.13-0.27). Patients did not report 91, 82, and 71% of audible cough events based on 1-, 2-, and 5-min concordance time windows, respectively.

We found that patients do not report the majority of their symptoms during ambulatory reflux monitoring even within a 5-min time window of the true event and advise caution in clinical decision-making based solely on symptom indices.