Association Between Hematological Indices of Inflammation and Pathogenesis and Prognosis of Sudden Sensorineural Hearing Loss: A Systematic Review and Meta-Analysis.

Chronic inflammation has been proposed as a contributing factor in the pathogenesis of sudden sensorineural hearing loss (SSNHL). The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and mean platelet volume (MPV) are well-established indices of inflammation, but their roles in SSNHL pathogenesis and prognosis remain controversial. This meta-analysis aimed to explore these associations. A systematic review was performed by 2 independent investigators across PubMed, Web of Science, Cochrane Library, and Embase databases. The quality of included studies was assessed using the Newcastle-Ottawa Scale. Twenty-six studies including 2392 SSNHL patients and 1865 controls were included. Recovery data were available for 1343 patients, of whom 785 recovered and 558 did not. Meta-analysis revealed that both NLR (standardized mean difference [SMD]=1.082, 95% CI=0.949, 1.216, P < .001) and PLR (SMD=0.516, 95% CI=0.333, 0.700, P < .001) were significantly elevated in SSNHL patients compared to controls. MPV (SMD=1.103, 95% CI=0.820, 1.483, P=.516) showed no significant difference. Additionally, higher NLR (SMD=-0.472, 95% CI=-0.784, -0.160, P=.003) and PLR (SMD=-0.327, 95% CI=-0.630, -0.023, P=.035) were associated with non-recovery in SSNHL, whereas differences in MPV (SMD=-0.352, 95% CI=-0.881, 0.177, P=.192) were not statistically significant. NLR and PLR may be involved in the pathogenesis of SSNHL and may serve as cost-effective and accessible prognostic markers.