NEFL and systemic lupus erythematosus: Complement C3 below lower limit of normal at the time of the study, any SLE-related organ damage (defined as SLICC/ACR-DI ≥ 1), ongoing treatment with glucocorticoids, non-antimalarial DMARDs or anti-hypertensives, and higher plasma creatinine concentrations were all associated with higher plasma log-NfL concentrations (Table 4).