Résumé
Data on the immunosuppressants azathioprine (AZA) and mycophenolate mofetil (MMF) in autoimmune cytopenia (AIC) are limited, and no direct comparison exists. We analyzed the failure-free survival (FFS) (time from AZA/MMF initiation to another non-first-line treatment or death) of both treatments in the prospective nationwide pediatric OBS'CEREVANCE cohort. We included 343 patients (chronic immune thrombocytopenia, n=161; autoimmune hemolytic anemia, n=74; Evans syndrome, n=108). They received AZA (n=276) or MMF (n=104; 37 sequentially received both) as monotherapy for a median (min-max) duration of 11.3 (0.01-149.0) months. Older age was associated with higher FFS for AZA, while secondary AIC was associated with higher FFS for MMF. AIC type had no effect. In a propensity score (PS)-matched cohort, AZA and MMF showed similar FFS (adjusted hazard ratio, 0.91; 95% confidence interval, 0.54-1.52; p=0.71), with 1-year FFS rates of 73% and 76%, respectively. In subgroup analyses, AZA was associated with higher FFS in PS-matched patients diagnosed at ≥10 years, whereas MMF was associated with higher FFS in PS-matched patients diagnosed at <10 years and in those with confirmed secondary AIC (although with suboptimal matching). Rates of grade ≥ 3 infection were similar between the two drugs, at approximately 2% new cases per year. In summary, AZA and MMF demonstrated comparable overall FFS and infection risk. However, our data suggest that AZA may be more beneficial in children diagnosed at ≥10 years, while MMF may be more beneficial in those diagnosed at <10 years and possibly in patients with secondary AIC.