Macrophage activation syndrome is associated with high in-hospital mortality in patients with lupus

Objective To study the clinical features and outcomes of macrophage activation syndrome in lupus. Methods This was a retrospective study conducted in a tertiary care referral centre from 2017 to 2022. Consecutive hospitalised adult-onset SLE patients diagnosed with MAS, fulfilling the Parodi criteria with ferritin >500 ng/ml were included. All the other hospitalised SLE patients without MAS served as controls. Clinical and immunological features and in-hospital mortality was compared between the 2 groups. Risk factors for mortality in MAS patients were determined performing univariate and multivariate analyses with a stepwise logistic regression. Results Of 623 hospitalisations in 451 SLE patients, 86 met the case definition for MAS and 526 served as controls. MAS occurred at the time of SLE diagnosis in 54 (62.9%). MAS was associated with fever, hepatosplenomegaly, lymphadenopathy, cytopenia, and elevated transaminases. Disease activity (clinical SLEDAI 2K) was significantly higher in MAS (mean 13.7 ± 6.5 vs. 8 ± 5.9 ( p < 0.001). In-hospital mortality was higher in the MAS compared to the control group [13 (15%) vs 6 (1%), p < 0.001]. Mortality in MAS was associated with higher ferritin (12092.9 ± 2826.5 vs 3993.6 ± 735, <0.001) and aspartate aminotransferase (544 ± 239 vs 167.66 ± 27.28U/L, p < 0.001), seizures ( p = 0.035), altered mental status ( p = 0.004), shock ( p < 0.001), intensive care unit admission ( p < 0.001), and mechanical ventilation ( p < 0.001). On multivariate regression analysis -ferritin >2400{OR-8.1 95% CI: (1.46-44.85) p - 0.017} and seizures {OR-7.3 95% CI: (1.2-44.29) p - 0.030} were associated with mortality in MAS. Conclusions MAS is a rare complication of active lupus identified by fever, elevated ferritin, liver transaminases and cytopenia and is associated with high in hospital mortality.