Background and Aims An urge of biomarker identification is needed to better monitor lupus nephritis (LN) disease activity, guide clinical treatment, and predict patient’s long-term outcome. With the proinflammatory effect and its association with inflammasomes, the significance of nterleukin-18 (IL-18) among pediatric-onset systemic lupus erythematous (pSLE) patient.

Methods In a pSLE cohort of 96 patients with an average follow-up period of 10.39±3.31 years, clinical data and laboratory workups including serum IL-18 were collected at time of disease onset and 6 months after treatment despite their initial renal status. Through Cox regression analysis, the parameters at baseline and at 6 months posttreatment were carefully analysed.

Results Average age of all cases was 12.74±3.01 years old and 65 of them underwent renal biopsy at the time of diagnosis. Nine(9.38%) progressed to end-stage renal disease (ESRD) and 2 (2.08%) died during follow-up. Through multivariate analysis, serum IL-18 level 6 months posttreatment was found to be the most unfavourable factor associating poor clinical outcome despite patient’s initial renal status. The presentation of serum IL-18 in its correlation with SLE global disease activity as well as the presence and severity of LN were all significant (p<0.001, p=0.03, and p=0.02, respectively). The histological classification of LN was not associated with the level of IL-18 among the pSLE patients (p=0.64).

Conclusions The role of serum IL-18 as biomarker representing global disease activity and status of renal flares among pSLE population was shown for the first time. Additionally, we have identified IL-18 at 6 months posttreatment a novel marker for long-term renal outcome prediction.