PurposeTo evaluate in France the annual direct medical cost of adult patients with active systemic lupus erythematosus (SLE) on medication and estimate the cost of a flare. MethodsA two-year, observational, retrospective, multicenter study, carried out between December 2010 and February 2011. Patients’ characteristics, SLE disease activity and severity, rate of flares, healthcare consumption (medications, hospitalisations, etc.) were evaluated. Medical costs were assessed from the national Health Insurance perspective. Cost predictors were estimated using multivariate regression models. ResultsEight centres specialized in SLE management included 93 eligible patients (including 50.5% severe). The mean age was 39.9 (11.9) years and 93.5% were women. At baseline, the mean SLE duration was 9.8 (6.6) years. The mean scores of the SELENA-SLEDAI instrument and the SLICC/ACR index were higher in severe patients (9.8 vs 5.6, and 1.2 vs 0.4 respectively; P<0.001). Over the study period, 51% of patients received the combination containing at least corticosteroids or immunosuppressants. The mean annual direct medical cost of severe patients was €4660 versus €3560 for non-severe patients (non-significant difference). The cost of medications (61.8% of the annual cost) was higher in severe patients (€3214 vs €1856; P<0.05). Immunosuppressants and biologics represented 26.5% and 4.6% of the annual total cost respectively. Patients experienced on average 1.10 (0.59) flares/year, of which 0.50 were severe flare. The occurrence of a new severe flare incremented the annual cost of €1330 (P<0.05). ConclusionMedications represented the major component of the annual direct medical cost. Severe flares increase significantly the cost of SLE care management.