Objective: To represent the effects of the severity of COVID-19 infection on platelet large cell ratio (PLC-R).

Materials and Methods: A hundred eleven patients diagnosed with COVID-19 were included in this study. Positive results for SARS-CoV-2 based on a typical RT-PCR test performed on nasopharyngeal swabs were included in the study Groups. Patients with COVID-19 were divided into three Groups according to their chest CT features. Group 1 (45 patients) was defined as mild, Group 2 (34 patients) as moderate and Group 3 (32 patients) as severe. Complete blood count parameters including platelet volume indices (PVI) values, CRP, D-dimer and lipid profiles were analyzed in all study participants. The correlation between COVID-19 patient Groups and PLC-R values were demonstrated using SPSS and ANFC methods.

Results: The significant impact of our study is that PLC-R was significantly higher in the severe COVID-19 patients than the moderate and mild patients. Spearman's rho correlation analysis showed that PLC-R and WBC levels increased, and Htc and Hb levels decreased with the severity of the disease. ROC analysis showed that PLC-R> 38.3% had 59.4% sensitivity and 68.4% specificity in predicting severe COVID-19 disease (AUC 0.672, %95 CI 0.560, 0.784; p=0.005, cut off=38.3). CRP, ferritin and D-dimer values of the patients in Group 3 were significantly higher than the patients in Group 1, and the iron values of the patients in Group 3 were significantly lower than the patients in Group 1.

Conclusion: PLC-R values are useful for anticipating acute thrombotic events. Based on the results of our study, PLC-R values can be used as appropriate biomarkers to describe the severity of COVID-19 infection.