Novel Systemic Inflammatory Indices (SII and SIRI) as Mediators Between BMI and Hearing Loss

This study aimed to examine the associations between body mass index (BMI) and hearing loss (HL), and to explore the mediating role of inflammation using data from the National Health and Nutrition Examination Survey (NHANES).

A cohort of 5489 participants aged ≥20 years from six NHANES cycles (2005-2012 and 2015-2018) was evaluated. Linear regression analysis was used to assess the relationships between BMI and HL. Three models were developed: (1) the association between BMI and low-frequency (LF) HL and speech-frequency (SF) HL; (2) the association between BMI and inflammatory markers (systemic immune-inflammatory index [SII] and systemic inflammatory response index [SIRI]); and (3) the association between SII/SIRI and LFHL/SFHL. Mediation analyses were conducted to evaluate the role of SII and SIRI in the relationship between BMI and HL.

Among the three groups, participants with higher BMIs exhibited higher values for SII, SIRI, LFHL, and SFHL. Positive correlations were observed between BMI and inflammation, inflammation and HL, and BMI and HL in all models. Mediation analysis revealed that SII mediated 9.87% of the effect of BMI on LFHL and 8.25% on SFHL, while SIRI mediated 17.47% and 16.59% of these effects, respectively. Although modest, these consistent mediating effects suggest inflammation contributes to, but does not wholly account for, the obesity-hearing relationship.

This study indicates that systemic inflammatory markers (SII and SIRI) partially mediate the association between BMI and HL. These findings suggest that inflammation represents a potential mechanistic link in obesity-related auditory dysfunction. Future longitudinal studies are needed to validate these pathways and inform targeted prevention strategies.