Broca-Garcia BE, et al. - In this cross-sectional study of 40 patients with systemic lupus erythematosus (SLE), researchers assessed the usefulness of neutrophil-to-lymphocyte ratio (NLR) plus C-reactive protein (CRP) to differentiate between infection and active disease. This study included patients without infection or active disease, patients with infection, patients with active disease, and patients with both infection and active disease. Patients with current malignancy, pregnancy, ischemic heart disease or use of antimicrobials during previous 7 days were excluded. With sensitivity 70%, specificity 85%, positive predictive value (PPV) 83% and negative predictive value (NPV) 74%, NLR cut-off ≥6.3 offered detection of patients with non-viral infections. Irrespective of SLE activity, a CRP cut-off ≥7.5 mg/L displayed sensitivity 90%, specificity 75%, PPV 78% and NPV 88% to detect infections. As a result of combining CRP and NLR, specificity improved to 90% and PPV to 88%. Overall, findings revealed the utility of CRP, particularly CRP plus NLR, in differentiating patients with SLE from those with suspected non-viral infection irrespective of disease activity.