Systemic immune-inflammation index (SII) as a prognostic marker of mortality in COVID-19 patients

Objective: To determine if the systemic immune-inflammation index (SII) is a prognostic marker of mortality in COVID-19 patients. Method: Retrospective study that included patients admitted to a general hospital in Mexico City with diagnostic of COVID-19, confirmed by quantitative polymerase chain reaction from nasopharyngeal swab specimens in addition to characteristic symptomatology and computerized thoracic tomography imaging. Upon admission an hematic biometry was taken to calculate the SII (neutrophils x platelets/lymphocytes). The optimal cut-off point was determined from a ROC curve; the chi-square test was used to evaluate the association of SII with mortality, the strength of the association was estimated through the odds ratio (OR) and, finally, a multivariate binary logistic regression analysis was performed. Results: 140 individuals were included, 86 (61.4%) men and 54 women (38.6%), the mean age of patients was 52 (& PLUSMN; 13.81) years old. The best prognostic cut-off point found was 2332.30 x 109 (area under the curve: 0.68; 95% confidence interval [95%CI]: 0.59-0.77; p < 0.05). The OR was 3.78 (95%CI: 1.83-7.82; p < 0.05). Conclusions: We demonstrated that the SII is an easily available tool, effective and a prognostic marker of mortality in hospitalized COVID-19 patients.