Differentiating flare and infection in febrile lupus patients: Derivation and validation of a calculator for resource constrained settings.

: Patients with Systemic Lupus Erythematous (SLE) are at an increased risk of infection and it is often difficult to differentiate between infection and disease activity in a febrile patient with SLE. : Patients with SLE (SLICC criteria) presenting with fever between December 2018 and August 2021 were included. Neutrophil to lymphocyte ratio (NLR), NEUT-x, -y, -z indices, Erythrocyte sedimentation rate (ESR), C-reactive protein(CRP), C3, C4, anti-dsDNA antibodies, and procalcitonin(PCT) were tested in addition to investigations as per the treating physician's discretion.