Study of Potential Utility of Predictive Laboratory Parameters for Early Triage of SARI Patients

Introduction: The novel corona virus (COVID-19), which began in Wuhan, China, in December 2019, has been declared pandemic by the World Health Organization (WHO) on 11th March 2021. Till now, even when nations are in race for developing vaccine against COVID-19, diagnosing the cases and isolating them still remain the only way to contain the disease spread. Hence, effective triage of the suspected COVID 19 patients, becomes an effective tool in preventing disease spread, especially in developing nations. Simple hematological parameters like leukocyte counts, platelet counts, hemoglobin and parameters derived from complete blood counts namely NLR, derived NLR, PLR and liver function tests can be studied and analysed to differentiate COVID 19 patients from other non-COVID 19 Severe Acute Respiratory Illness (SARI) patients. These are the investigations at first point of contact with the patient and are relatively cost effective, keeping in mind the population of developing nations.

Patients and Methods: Retrospective case control study conducted over a period of one month including 286 consecutive Severe Acute Respiratory Illness(SARI) patients admitted in a tertiary care hospital in Delhi. The patients were divided into COVID-19 positive and COVID-19 negative groups based on their results of reverse transcriptase-polymerase chain reaction (RT-PCR) for COVID-19. The demographic data, and routine hematological and biochemical parameters including derived parameters like Neutrophil lymphocyte ratio (NLR), derived NLR ratio, Platelet lymphocyte ratio (PLR) and Prognostic nutrition index (PNI) were analyzed and compared between the two groups using SPSS version 23.0. A p value of <0.05 was considered significant.

Results: The COVID-19 positive patients had a significantly higher lymphocyte percentage (p value=0.017) and Serum Glutamate Pyruvate Transaminase(SGPT)( p value=0.033), and a significantly lower Absolute Neutrophil Count (ANC)( p value= 0.023), NLR(p value=0.033) and platelet count(p valu=0.001). No significant difference in other haematological and biochemical parameters was found.

Conclusion: NLR, platelet count, lymphocyte percentage and SGPT are the simple laboratory biomarkers of inflammation that can be utilized for screening and triage in COVID 19 disease with variable sensitivity and specificity.