Systemic inflammatory and metabolic biomarkers in relation to initial hearing loss severity in sudden sensorineural hearing loss

To assess whether routinely measured systemic inflammatory and metabolic biomarkers are related to the initial severity of hearing impairment in patients presenting with sudden sensorineural hearing loss (SSNHL). This retrospective case-control study included 613 adult inpatients with SSNHL treated between January 2020 and December 2024 and 850 healthy individuals undergoing routine health examination during the same period. Hearing loss severity was classified into mild, moderate, severe, and profound categories according to the baseline pure-tone average (PTA)-based audiological assessment. Continuous variables were summarized as median (interquartile range) and compared using non-parametric tests. Associations with PTA-defined severity were evaluated using ordinal logistic regression, with sequential adjustment for demographic and metabolic covariates. Collinearity, model fit, proportional odds assumption, missingness, and sensitivity analyses were assessed. Compared with controls, patients with SSNHL had higher total cholesterol, LDL-C, glucose, neutrophil count, NLR, platelet count, PLR, MPV, and ApoA1, and lower lymphocyte count and triglycerides. Among patients with SSNHL, the severity distribution was mild in 320 patients (52.2%), moderate in 155 (25.3%), severe in 88 (14.4%), and profound in 50 (8.1%). Across severity categories, albumin and HDL-C tended to decrease, whereas age, glucose, triglycerides, fibrinogen, and D-dimer tended to increase. In ordinal logistic regression, albumin was associated with severity in the biomarker-only model (OR 0.928, 95% CI 0.880–0.978, P = 0.006), but this association was attenuated after adjustment for age, sex, glucose, triglycerides, and HDL-C (OR 0.970, 95% CI 0.915–1.028, P = 0.302). Age, male sex, and glucose remained associated with greater severity in the fully adjusted model. SSNHL was accompanied by detectable systemic inflammatory and metabolic differences compared with controls. However, initial hearing loss severity was not independently explained by NLR, PLR, LDL-C, or albumin after adjustment for demographic and metabolic covariates. Albumin may be considered a candidate marker of systemic nutritional-inflammatory status, but its severity-related association should be interpreted cautiously and requires prospective validation.