Sex- and gender-specific differences in the inflammatory response to COVID-19: the role of the neutrophil-to-lymphocyte ratio

INTRODUCTION: The neutrophil-to-lymphocyte ratio (NLR) is a simple blood test marker used to predict the severity of COVID-19. The study aimed to describe the correlation between neutrophil-to-lymphocyte ratio sex- and gender-specific differences in the inflammatory response to COVID-19. MATERIAL AND METHODS: This retrospective observational study was conducted with patients diagnosed with COVID-19 in the emergency department of a tertiary hospital between January 1, 2022, and May 31, 2022. The receiver operating characteristic (ROC) area under the curve (AUC) analysis was conducted to verify NLR predictive capacity. RESULTS: The study population consisted of 47% women and 53% men with a mean age of 72.42 years. Women were significantly older than men on average. At admission, 73% of patients were classified as nonsevere, while 27% were severe. Overall, 63% of patients survived the infection. CONCLUSIONS: There were slight but not statistically significant differences in neutrophil counts between men and women. However, there were significant differences in lymphocyte counts and the NLR, with women having higher lymphocyte counts and men having higher NLR. The study found very weak correlations between age and neutrophil counts, lymphocyte counts, and NLR, suggesting no strong relationship between age and these variables. Patients with severe disease had higher neutrophil counts and NLR but lower lymphocyte counts compared to nonsevere patients. Survivors had lower neutrophil counts and NLR but higher lymphocyte counts compared to those who did not survive. NLR was a significant predictor of both admission status and survivor status, with ROC AUC values indicating its predictive capacity. These findings highlight the potential importance of NLR as a biomarker in predicting disease severity and survival in patients.