Improved diagnostic yield of symptom association probability involving only cough for gastroesophageal reflux-induced chronic cough

Background: Use of symptom association probability (SAP) is recommended for identifying gastroesophageal reflux-induced chronic cough (GERC). This study aimed to compare the diagnostic yield of SAPs involving only cough (C-SAP) or total symptoms (T-SAP) for GERC identification.Methods: Patients with both chronic cough and other reflux-related symptoms underwent multichannel intraluminal impedance-pH monitoring (MII-pH) between January 2017 and May 2021. C-SAP and T-SAP were calculated based on the patient-reported symptoms. GERC was definitively diagnosed by the favorable response to anti-reflux therapy. The diagnostic yield of C-SAP in identifying GERC was evaluated by receiver operating characteristic curve analysis and compared with that of T-SAP.Results: MII-pH was performed in 105 patients with chronic cough, and GERC was confirmed in 65 (61.9%), including 27 (41.5%) cases of acid GERC and 38 (58.5%) cases of non-acid GERC. The positive rates of C-SAP and T-SAP were comparable (34.3% vs. 23.8%, P>0.05), but C-SAP exhibited a higher sensitivity (53.85% vs. 33.85%, chi 2=8.117, P=0.004) and similar high specificities (97.5% vs. 92.5%, P>0.05) compared with T-SAP for GERC identification. C-SAP was also more sensitive for recognition of acid GERC (51.85% vs. 33.33%, chi 2=7.386, P=0.007) and non-acid GERC (65.79% vs. 39.47%, chi 2=14.617, P<0.001). More GERC patients with positive C-SAP needed intensified anti-reflux therapy for cough resolution when compared with those with negative C-SAP (82.9% vs. 46.7%, chi 2=9.449, P=0.002). Conclusions: C-SAP was superior to T-SAP for the identification of GERC and may improve the diagnostic yield of GERC.