Utility of Serum Procalcitonin and Its Clearance in Predicting Outcomes in COVID-19 Patients

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Introduction Identification of coronavirus disease 2019 (COVID-19) patients at risk of worse clinical outcomes is crucial to improving patient care. Various biochemical markers have been used to predict outcomes in such patients. We aimed to evaluate the role of serum PCT (procalcitonin) and the utility of PCT clearance (PCTc) in predicting the outcome of patients with COVID-19 illness. Methods We prospectively included 39 patients with severe or critical COVID-19 illness with an age equal to more than 18 years. In addition to routine baseline investigations, serum PCT was measured at admission (PCT1) and day 5 of hospitalization (PCT2). PCTc was calculated using the formula \((PCTc (\%) = (PCT1-PCT2/PCT1) x 100)\). Results We observed that serum PCT at admission was significantly higher in non-survivors (median: 1.9 ng/ml IQR: 0.51-4.23) compared to survivors (median 0.35 (IQR: 0.1-1.2), p 0.002). On serial serum-PCT estimation, non-survivors had persistently elevated serum-PCT (median PCT1:1.9 ng/ml (IQR: 0.51-4.23) to median PCT2: 1.9ng/ml (IQR: 0.83-2.72), p 0.51) than survivors (median PCT1:0.35ng/ml (IQR: 0.1-1.19) to median PCT2: 0.15ng/ml (IQR: 0.05-0.29), p 0.01). However, no difference in serum PCTc was observed between the two groups (median: 35.3% (IQR: 12.5-84.9) in survivors vs. 71.7% (33.3-91.7) in non-survivors, p = 0.165). Conclusion Serum PCT is a potential biochemical marker that could predict outcomes in COVID-19 patients. Measurement of serial serum PCT and estimation of PCT clearance may serve as better predictors than a single value; however, well-designed studies are required to identify the definite role of serum PCT in COVID-19 patients of varying severity.