Association between routine hematological parameters and sudden sensorineural hearing loss: A meta-analysis

OBJECTIVE: Recent studies have shown that chronic inflammation contributes to the development of sudden sensorineural hearing loss (SSNHL). Some hematologic parameters have also been linked to the prognosis of SSNHL. However, the prognostic value of such hematological factors is not conclusive. This study explored the association of routine hematological parameters with SSNHL. METHODS: A systematic literature search was conducted in PubMed, Cochrane Library, Web of Science and Embase to identify eligible studies. Standardized mean deviation (SMD) and the 95% confidence interval (CI) were retried from relevant studies for analysis. Heterogeneity, subgroup, and publication bias analyses were performed. RESULTS: A total of 18 studies involving 1505 SSNHL patients and 1466 healthy persons were enrolled in the final analysis. The study population included 699 responders and 458 non-responders to treatment. Pooled results revealed that the neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) value in the SSNHL patient group were higher than in the healthy group (SMD = 1.05, 95% CI: 0.86,1.24, p < 0.001, SMD = 0.52, 95% CI: 0.26,0.78, p < 0.001, respectively). However, there was no significant difference in the mean platelet volumes (MPV) between the groups (SMD = 0.03, 95% CI: 0.44, 0.49, p = 0.91). Notably, NLR and PLR values were evidently higher in the unrecovered group than in the recovered group (SMD = −0.63, 95% CI: 1.02, −0.23, p = 0.002, SMD = −0.4, 95% CI: 0.76, −0.03, p = 0.03, respectively). However, the MPV value was similar in both groups (SMD = −0.35, 95% CI: 1.14,0.44, p = 0.38). CONCLUSIONS: Our results show that NLR and PLR values can predict the onset and prognosis of SSNHL.