Background Our aim was to explore the correlation between the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI 2K) at the time of diagnosis and the SLICC/ACR damage index (SDI) of patients at their last follow up, to examine organ damage and to predict the risk of organ damage occurrence in time.

Methods The retrospective study included children with childhood onset systemic lupus erythematosus (cSLE) treated from 1991 to 2017 at University Hospital Centre Zagreb.

Results 93 children (74 females and 19 males) with cSLE were examined with median (range) follow up time of 7 (0.5–24) years and the median (range) age at diagnosis of 13 (5–19) years. Mean (SD) SLEDAI-2K was 18.3 (9.0) at the disease onset. 38% had organ damage at the last follow up with the median (range) SDI 0 (0–7). The first organ systems damaged in affected patients were renal (28%), musculoskeletal (22%), ocular (19%), neuro-psychiatric (17%), cardiovascular (11%) and peripheral vascular (2.8%), but with no significant statistical difference regarding the type of organ damage. Kendall rank correlation coefficient determined a positive correlation between SLEDAI-2K at the disease onset and SDI (τb=0.252, p=0.003). There was no significant difference of SDI in regard to gender (Asymptotic Wilcoxon-Mann-Whitney Test, p=0.574). Using Kaplan-Meier method we estimated with 95% confidence the damage is not happening in the first 9 or 10 years after diagnosis or the occurrence of the first symptoms.

Conclusions The high correlation between SLEDAI-2K and SDI indicated that the presentation of the cSLE at onset can be prognostic of the course and long-term prognosis of lupus. Our findings suggest it is unlikely that organ damage will occur in 50% of patients in the first nine years of the disease course.