Biomarker-guided use of corticosteroids in pneumonia.

Community-acquired pneumonia (CAP) is one of the leading causes of death worldwide. Although corticosteroids have been proposed as immunomodulatory, controversies surrounding the results of clinical trials have limited their widespread use. This review aims to determine which biomarker-guided corticosteroid treatment for CAP is generally agreed upon in the latest published studies and to discuss the main aspects to be taken into consideration based on lessons learnt from patients with conditions such as influenza, SARS-CoV-2 infection or the recently identified subphenotypes in acute respiratory distress syndrome (ARDS). Most studies have demonstrated that high C-reactive protein concentrations at the time of admission are associated with a hyperinflammatory state and that patients are more likely to benefit from corticosteroid treatment if they have high concentrations. High levels of C-reactive protein (CRP) were used as an inclusion criterion in one clinical trial, demonstrating that treatment failure was reduced in the corticosteroid group. A post-hoc analysis of the results of several studies also showed that CRP levels above 200 mg/L were associated with benefits in patients receiving corticosteroids. Recent guidelines have proposed the use of corticosteroids in patients with severe CAP or septic shock. Corticosteroids could be more beneficial for patients with a hyperinflammatory subphenotype; however, there are currently no prospective studies evaluating this approach. Further studies are needed to clarify the role of biomarkers in personalised medicine for patients with CAP. In the meantime, patients with severe CAP or high CRP levels should be treated with corticosteroids.