Picard C, et al. – The accuracy of anti–C1q autoantibodies (Abs) was analyzed to predict renal flare and global disease activity in childhood–onset systemic lupus erythematosus (cSLE) patients. Anti–C1q Abs appeared to be very specific to flares, including lupus nephritis (LN) in children. However, further research work was required to determine their role in daily practice.

Methods

• This study consisted of 28 patients with cSLE including 19 patients (68%) with a history of LN.
• Anti–C1q Abs were analysed by ELISA at renal flare–up or in the quiescent phase of disease and compared with Farr dsDNA assay.

Results

• During follow–up 31 flares occurred: anti–C1q Abs were positive in 26 (84%), strongly associated with active disease status (p < 0.0001), and correlated with global disease activity score (p < 0.0001) and anti–dsDNA Abs presence (p < 0.0001).
• In discriminating LN patients, the specificity of anti–C1q Abs was higher than anti–dsDNA (73% vs 19%), whereas the receiver operating characteristic curves were not statistically different (0.83 ± 0.06 vs 0.78 ± 0.08 respectively), similar to C3 dosage.
• The presence of anti–C1q Abs at diagnosis was not predictive for global or renal flare.
• Introduction of a modified SLEDAI score excluding dsDNA Abs, demonstrated a stronger correlation of anti–C1q Abs titres with SLEDAI score in comparison with the Farr test.