Meta-analysis of the systemic immune-inflammatory index and in-hospital mortality of COVID-19 patients

Abstract

BackgroundThe potential significance of immunoinflammatory factors in the prognosis of individuals afflicted with coronavirus disease 2019 (COVID-19) is worthy of examination. The systemic immune-inflammatory index (SII), a recently developed immunoinflammatory metric based on the enumeration of neutrophils, platelets, and lymphocytes in blood samples, holds promise for elucidating this relationship. Consequently, in order to explore any possible correlation between the SII levels at admission and the in-hospital mortality of patients with COVID-19, we undertook a thorough systematic review and meta-analysis. MethodsIn pursuit of accomplishing the aim of this meta-analysis, an extensive search was conducted to seek out pertinent observational studies featuring longitudinal follow-up across PubMed, Cochrane Library, Embase and the Web of Science databases. The I2 statistic was utilized to estimate the extent of heterogeneity and the Cochrane Q test was employed to evaluate heterogeneity between studies. The synthesis of outcomes involved the use of random-effects models, accounting for the possible influence of heterogeneity. ResultsOur analysis included sixteen studies, encompassing 10,007 hospitalized COVID-19 patients. Among them, 1801 patients (18.0 %) succumbed during hospitalization. The pooled results indicated that a high SII at admission was substantially linked to a higher risk of all-cause mortality (risk ratio [RR]: 2.41, 95 % confidence interval: 1.78 to 3.24, p < 0.001; I2 = 86 %). Meta-regression analysis demonstrated a negative correlation between mean SII at baseline and patient mortality in individual studies (coefficients = −0.00023 and −0.030, p < 0.05), effectively explaining the observed heterogeneity. Furthermore, in patients with lower baseline SII (<1300) and a lower risk of mortality (<20 %), we observed a more pronounced association between high SII levels and the risk of all-cause mortality. ConclusionThe results of our study indicate that a high SII upon admission could potentially function as a prognostic indicator for mortality during hospitalization in patients diagnosed with COVID-19, particularly in individuals categorized as low risk.