Neutrophil-to-lymphocyte and platelet-to-lymphocyte ratio predicting hospital length of stay and mortality in young COVID-19 patients: A retrospective study

Background This study investigated the utility of platelet-to-lymphocyte ratio (PLR) and Neutrophil-to-Lymphocyte ratio (NLR) in patients with COVID-19 with respect to age, early (a week) vs. delayed recovery (> a week) and mortality. Methods This was a retrospective study including 1,016 COVID-19 patients. The discriminatory power and multivariate logistic regression analysis were performed. Results The mean age of patients was 45 (± 13.9), and 75.7% were males. Older patients had elevated NLR, PLR, D-dimer, CRP, and Interleukin-6 levels and longer hospital stay than the younger group (p < 0.001). In-hospital mortality was higher in older adults (26.9% vs. 6.6%, p =0.001). On-admission NLR (5.8 vs. 3.2; P= 0.001) and PLR (253.9±221.1 vs. 192.2±158.5; p = 0.004) were higher in the non-survivors than survivors. Both PLR and NLR displayed significant discriminatory ability for mortality. NLR had a higher AUC and specificity, while PLR exhibited slightly higher sensitivity. In individuals aged ≤55, NLR showed superior discrimination (AUC=0.717) compared to PLR (AUC=0.620). Conversely, for older adults, PLR displayed enhanced discrimination (AUC=0.710), while NLR showed AUC=0.693. Conclusion Higher admission NLR and PLR levels were associated with delayed recovery, whereas an enhanced NLR was associated with considerably higher mortality in older COVID-19 patients.