Role of cystatin C and calprotectin as potential early prognostic biomarkers in COVID-19 patients admitted to a dedicated COVID care facility

BACKGROUND: The COVID-19 pandemic has claimed millions of lives. A tool for early prediction of severity and mortality risk is desirable for better utilization of health care facilities. Several biomarkers like D-dimer, lactate dehydrogenase (LDH), C-reactive protein (CRP) and some recently explored biomarkers like serum cystatin C and serum calprotectin have been proposed as prognostic markers of COVID-19, but their role as prognostic markers is so far undefined. The present work attempted to investigate the possible role of serum cystatin C and serum calprotectin as prognostic tools to predict severity and outcome ahead of time. MATERIAL AND METHODS: This observational cohort study was carried out on 95 COVID-19 patients admitted to a dedicated COVID care facility from mid-October 2020 to January 2021. Serial estimations of serum cystatin C and serum calprotectin levels were done and assessed for significant difference between severe (NEWS 2 score ≥5) and non-severe (NEWS 2 score <5) groups, survivors and deceased and on the basis of comorbidities at each time points. Survival analysis was done based on the optimal thresholds for severity and mortality, calculated from the receiver operating characteristic (ROC). RESULT: The results showed that median cystatin C levels were significantly higher on the first day in the severe group (P < 0.001) and in patients with cardiovascular disease (P < 0.05), chronic lung disease (P = 0.009) and among patients who died (P < 0.05). It remained raised on day 3 in severe (P < 0.05) and deceased (P < 0.05) group. Serum calprotectin levels were significantly higher in patients with chronic lung disease (P = 0.008) and in those who died (P < 0.05). CONCLUSION: Serum cystatin C could be used as a tool for early prognosis and therapeutic decision-making for COVID-19 patients. Serum calprotectin seems to be a better marker of critical illness.