Mean nocturnal baseline impedance predicts increased pharyngeal reflux on hypopharyngeal-esophageal pH-impedance monitoring in patients with laryngopharyngeal symptoms.

Laryngopharyngeal symptoms (LPS) present a diagnostic challenge due to the lack of clear diagnostic gold standard, and suboptimal correlation between traditional esophageal reflux criteria and pharyngeal reflux events. Mean nocturnal baseline impedance (MNBI) is a measure of mucosal integrity that correlates with reflux burden, but evidence for its role in diagnosing laryngopharyngeal reflux disease remains limited. We aimed to characterize the correlation between MNBI and pharyngeal reflux on objective reflux monitoring. This was a retrospective study of adults with LPS undergoing reflux monitoring with hypopharyngeal-esophageal multichannel intraluminal impedance and pH. MNBI was calculated by taking the mean baseline impedance of three 10-minute time periods at rest (1 AM, 2 AM, 3 AM) from the distal electrode pairs (9-11 cm/11-13 cm below the upper esophageal sphincter). Increased pharyngeal reflux was defined as ≥2 events in 24 hours per established criteria. Univariate, multivariable, and receiver-operating characteristic (ROC) curve analyses were performed. One hundred nineteen patients were included (mean age = 55.5 ± 1.4 years, 71.4% female). MNBI inversely correlated with pharyngeal reflux events (r = -0.25, P = 0.009) and was lower in patients with increased pharyngeal reflux (1867 ± 124 Ω vs. 2540 ± 177 Ω, P = 0.0027). On multivariable analysis, MNBI remained independently predictive of increased pharyngeal reflux (OR: 0.94 per 100 Ω increase, 95% CI:0.90-0.98, P = 0.008). On ROC analysis, the area under ROC curve for increased pharyngeal reflux was 0.65, with MNBI thresholds of 1017 Ω and 3474 Ω achieving >90% specificity and sensitivity, respectively. Lower MNBI independently predicts increased pharyngeal reflux in patients with LPS, with potential adjunctive value for laryngopharyngeal reflux disease diagnosis on objective testing.