The role of biomarkers in diagnosis of COVID-19 – A systematic review

As of the 28th April 2020, the COVID-19 pandemic has infiltrated over 200 countries and affected over three million confirmed people. We review different biomarkers to evaluate if they are able to predict clinical outcomes and correlate with the severity of COVID-19 disease. A systematic review of the literature was carried out to identify relevant articles using six different databases. Keywords to refine the search included ‘COVID-19’, ‘SARS-CoV2’, ‘Biomarkers’, among others. Only studies which reported data on pre-defined outcomes were included. Thirty-four relevant articles were identified which reviewed the following biomarkers: C-reactive protein, serum amyloid A, interleukin-6, lactate dehydrogenase, neutrophil-to-lymphocyte ratio, D-dimer, cardiac troponin, renal biomarkers, lymphocytes and platelet count. Of these, all but two, showed significantly higher levels in patients with severe complications of COVID-19 infection compared to their non-severe counterparts. Lymphocytes and platelet count showed significantly lower levels in severe patients compared to non-severe patients. Although research is still in its early stages, the discovery of how different biomarkers behave during the course of the disease could help clinicians in identifying severe disease earlier and subsequently improve prognosis. Nevertheless, we urge for more research across the globe to corroborate these findings. •There are many biomarkers with suggested roles in monitoring COVID-19 infection.•Increases in CRP and D-dimers have strong associations with mortality.•Likewise, decreases in platelet count strongly associated with mortality.•Ultimately more research is needed to determine prognostic benefit.