Anti-C1Q monitoring predicts relapses of lupus nephritis

To the Editor, Lupus nephritis (LN), a frequent complication of systemic lupus erythematosus (SLE), contributes significantly to the risk of mortality and renal failure [1 ].The course of LN is characterized by periods of remission and exacerbation.Renal flares require timely diagnosis and management to avoid the risk of transformation of inflammatory into chronic lesions [2 ].Non-invasive biomarkers to confirm the clinical diagnosis of renal flares are essential for clinicians.Anti-C1q antibodies (anti-C1qAb), present in 30%-50% of SLE patients [3 , 4 ], may predict LN development [5 , 6 ], particularly in its proliferative forms [4 , 7 ].Data about the association between anti-C1qAb levels and the occurrence of renal flares are lacking.This retrospective analysis on biopsy-proven active LN patients, prospectively followed in a nephrological unit, aimed to investigate the association between regular anti-C1qAb monitoring and renal flare occurrence.We also assessed, as potential predictors of renal flares, the variables at baseline and at 6 and 12 months post-induction therapy, reported in Supplementary Table 1.Both univariable and multivariable analyses were performed with Coxregression models.Stepwise regression was used for multivariable