P84 Regular monitoring of anti-C1q antibodies can be of help to predict lupus nephritis (LN) exacerbations

Objective This study explores the role of monitoring anti-C1q antibodies to predict lupus nephritis (LN) flares. Methods In a cohort of LN patients, their clinical/histological/immunological/therapeutic features, at start of study, at 6 and 12 months after beginning therapy (reported in table 1) were tested at univariable and multivariable analysis with Cox proportional hazard models to identify predictors of renal flares occurring after 12-months follow-up. Anti-C1q antibodies were measured by ELISA-test (normal value were 80UA). Results Fifty-three LN patients (84.9% were females, with a median age of 39 (29–47) years old, 10 patients with class III, 39 class IV and 4 class V at kidney biopsy categorized by ISN/RPS classification), 36 enrolled at LN diagnosis and 17 at a LN flare, entered this study. At baseline, 17 patients had acute kidney dysfunction (32%), and 17 had nephrotic syndrome (32%). Forty patients received methylprednisolone pulses as induction therapy, the others oral prednisone (0.5–1mg/kg/day) associated with an immunosuppressive agent. During a median follow-up of 62.5 (45.63–78.62) months, renal flares occurred in 10 patients (18.86%). All flares occurred after 12-months observation, in median 28.19 (24.84–39.38) months (2 nephritic and 8 proteinuric flares). Among clinical/histological and therapeutic features at start of the study and at 6 months, only anti-C1q antibodies (OR:1.0098; CI:1.0004–1.0193; p=0.04; OR:1.0268; CI:1.0126–1.1041; p=0.001 respectively) predicted renal flares. At 12 months, anti-C1q antibodies (OR:1.0180; CI:1.0064–1.10297; p=0.0020), antiC1q >40 UA (OR:4.4345; CI:1.1536–17.0462; p=0.0310), proteinuria (OR:1.8537; CI:1.1237–3.0578; p=0.0160), and no use of hydroxychloroquine (OR:0.2561; CI:0.1009–1.2778; p=0.0370) predicted renal flares at univariable analysis. At multivariable analysis, antiC1q >40 UA (OR:5.2421; CI:1.3338–20.6019; p=0.0183) and no use of Hydroxychloroquine (OR: 0.2080; CI:0.0538–0.7573; p=0.0183) were the independent predictors of renal flares (figure 1). Conclusion With the limitations of a small study, our results suggest that a high titer of anti-C1q at baseline and failure to normalize (or reducing <40 UA) during the follow-up are helpful in identifying patients who will develop renal flares. Hydroxychloroquine use reduces the risk of lupus flares.