Comparison of neutrophil-lymphocyte ratio among severe acute respiratory illness COVID-19 positive and negative patients and to correlate with disease severity

Abstract

Background: COVID-19, a pandemic caused by SARS-CoV-2, has caused a wide impact globally. Clinical spectrum of COVID-19 ranges widely including asymptomatic infection, mild upper respiratory tract infection, severe pneumonia, ARDS, MODS and even death. Neutrophil-lymphocyte (NL) ratio is an indicator of systemic inflammatory response. Many previous studies have shown NL ratio to be good prognostic marker for COVID-19 pneumonia.Methods: A study was conducted on 265 SARI (severe acute respiratory illness) patients who were admitted in hospitals attached to BMCRI between May 2020 and September 2020. History was taken, general and systemic examination was done. Patients were categorized into moderate and severe illness. RT-PCR for all patients was done using throat and nasal swab. Total WBC counts and differential counts were estimated. NL ratio was correlated with pneumonia severity and compared between COVID-19 positive and negative SARI.Results: The study included 265 SARI patients, of which 135 were COVID-19 positive patients and 130 were COVID-19 negative. The patients were further sub-categorised into moderate and severe SARI. Mean age for COVID-19 positive severe SARI was higher than the moderate SARI. Males were majority of the subjects. Out of 265, 99 patients (37.4%) had diabetes. Out of this, 34 (42%) were COVID-19 positive (severe) followed by 28 (51.9%) COVID-19 positive (moderate). Mean NL ratio was higher in COVID-19 positive (severe) subjects 15.95±10.31 followed by COVID-19 positive (moderate) subjects 8.99±6.22. There was significant difference with respect to NL ratio between COVID-19 positive and negative subjects. NL ratio levels were high in subjects having diabetes in COVID-19 positive severe sub group and COVID-19 positive severe hypertension sub group as compared to other sub groups.Conclusions: NL ratio was higher in patients with COVID-19 positive SARI as compared to COVID-19 negative SARI. There was significant correlation between increase in NL ratio and disease severity of COVID-19 positive pneumonia. We found that increase in NL ratio was associated with co-morbidities like diabetes mellitus and hypertension.