Effect of probiotic lozenges on improvement in tympanometric classification within 12 weeks in children aged 3–6 years with adenoid hypertrophy and otitis media with effusion undergoing non-surgical management: a randomized controlled trial

Background: Otitis media with effusion (OME) is common among children aged 3-6 years with adenoid hypertrophy. Restoring middle-ear ventilation and clearing effusion are key goals during non-surgical management, and tympanogram classification serves as the main clinical indicator. The probiotic Streptococcus salivarius K12 (SSK12) can colonize the upper airway and inhibit pathogens, yet randomized trials using tympanogram classification as the primary endpoint are limited. Objective: CFU) for 12 weeks on tympanogram classification improvement in children with adenoid hypertrophy and OME and to elucidate related microecological, pathogenetic, and audiological pathways, along with safety and internal validity measures. Methods: A single-center, randomized, double-blind, placebo-controlled RCT was conducted. All participants received standard non-surgical management and were allocated to either SSK12 or placebo lozenges for 12 weeks. The primary outcome was child-level tympanogram improvement ("B/C→A") at week 12. Secondary analyses included ear-level results, tympanometric parameter changes, audiometric outcomes, and nasopharyngeal microbiota profiles. Logistic regression, generalized estimating equations (GEE), and linear mixed-effects models were employed to estimate adjusted odds ratios (aORs), interaction terms, and time effects. Results: Compared with placebo, SSK12 significantly increased the probability of tympanogram improvement (aOR=1.87, P = 0.003), with consistent benefits across subgroups (all p(interaction)>0.05). Ear-level analyses confirmed the advantage (all aOR>1, P