Macrophage Activation Syndrome in Patients Affected by Adult-onset Still Disease: Analysis of Survival Rates and Predictive Factors in the Gruppo Italiano Di Ricerca in Reumatologia Clinica E Sperimentale Cohort

Objective. Macrophage activation syndrome (MAS) is a reactive form of hemophagocytic lymphohistiocytosis, which can complicate adult-onset Still disease (AOSD). We investigated AOSD clinical features at the time of diagnosis, to assess predictors of MAS occurrence. Further, we analyzed the outcomes of patients with AOSD who experience MAS. Methods. Patients with AOSD admitted to any Gruppo Italiano di Ricerca in Reumatologia Clinica e Sperimentale center were retrospectively analyzed for features typical of AOSD, MAS occurrence, and their survival rate. Results. Of 119 patients with AOSD, 17 experienced MAS (12 at admission and 5 during followup). Twelve patients with MAS at first admission differed from the remaining 107 in prevalence of lymphadenopathy and liver involvement at the time of diagnosis. In addition, serum ferritin levels and systemic score values were significantly higher in the patients presenting with MAS. At the time of diagnosis, the 5 patients who developed MAS differed from the remaining 102 in the prevalence of abdominal pain, and they showed increased systemic score values. In the multivariate analysis, lymphadenopathy (OR 7.22, 95% CI 1.49-34.97, p = 0.014) and abdominal pain (OR 4.36, 95% CI 1.24-15.39, p = 0.022) were predictive of MAS occurrence. Finally, MAS occurrence significantly reduced the survival rate of patients with AOSD (p < 0.0001). Conclusion. MAS occurrence significantly reduced the survival rate in patients with AOSD. Patients with MAS at baseline presented an increased prevalence of lymphadenopathy and liver involvement, as well as high serum ferritin levels and systemic score values. The presence of lymphadenopathy and abdominal pain was associated with MAS occurrence.