Neutrophil-to-lymphocyte ratio and D-dimer assay in prediction of disease severity in covid positive Indian patients in a tertiary care centre

ABSTRACT

Aims & Objectives: To evaluate role of hematological parameters in prediction of disease severity and also analyze the trends of NLR and D-Dimer during its course. Patients/Materials & Methods: A retrospective analysis of 83 patients diagnosed with COVID-19 by RT-PCR at Medanta-the Medicity hospital in June 2020 was done. The data included neutrophil- to-lymphocyte ratio (NLR), D-Dimer, PT/APTT and platelet count. The patients were divided into 20 critical patients and 63 Noncritical patients group, based on disease severity. The parameters were compared and trends analyzed. Results: The COVID positive cases had a mean age of 56.7 years (Range 7-84 years) with a malefemale ratio of 2.61. The critical group had mean age of 64.7 years (Range 42-76), versus 54.1 years (Range 7-84) in non-critical group. At admission, the mean NLR in the critical and non-critical group was 12.26 and 5.7. Further, the critical and non-critical group had NLR>3.13 in 19 cases (95%) and 49 cases (77.8%), respectively. On receiver operating characteristic curve (ROC) analysis, predictive ability of NLR for detection of critical patients was significant(p value = 0.0001;AUC0.779) with optimal cut-off value of 6.01, having 85% sensitivity, 68.9% specificity and ∼ 93.5% negative predictable value (NPV). The mean D-Dimer value in critical and non-critical group on Day-4 of admission was 18.89 mg/L and 2.48 mg/L. Moreover, the D-Dimer>0.55 mg/L were seen in 17 critical cases (85%) in contrast with 35 non-critical cases (55.5%). On ROC analysis, the ability of D-Dimer in predicting disease severity was significant( p value = 0.0001;AUC0.896) with optimal cut-off value of 2.27 mg/L, having 85% sensitivity, 76.2% specificity and NPV ∼ 94.1%. On trend analysis, it was observed that the D-Dimer and NLR showed a progressive upward trend in critical patients, whereas there were more of plateau/declining values in non-critical patients. PT was mildly prolonged in 14 critical patients (70%) and 13 non- critical patients (40.6%). The mean platelet counts were similar in both the groups. Discussion & Conclusion: The study shows that the severity of the disease is more in elderly (Mean age 64.7 years). Also, at admission NLR>6.05 and Day-4 D-Dimer>2.27 mg/L are significantly predictive of disease severity and such patients should receive prompt treatment to minimize further sequel and morbidities.