Schafer VS, et al. - Authors conducted a retrospective analysis to evaluate the disease activity parameters in patients with systemic lupus erythematosus (SLE) experiencing flare, infection, both, or neither condition, focusing on erythrocyte sedimentation rate (ESR). ESR levels were related to an age- and gender-adapted cut-off value (ESRp). Findings suggested a relation of ESRp, serositis, and anti-dsDNA antibodies with disease activity regardless of infections. For detecting flares, anti-dsDNA antibodies were most sensitive, while serositis, proteinuria with erythrocyturia, anti-dsDNA antibodies, C3 reduction, and ESRp values ≥ 2 were most specific. Flares, infections, and age raised the ESR levels. Adapting these factors to age and gender increased their diagnostic value. In order to differentiate flare from infection, obtaining several parameters remained necessary.