Characteristics and Outcomes of Patients with Systemic Lupus Erythematosus-associated Thrombotic Microangiopathy, and Their Acquired ADAMTS13 Inhibitor Profiles.

OBJECTIVE: To investigate the characteristics and outcomes of patients with systemic lupus erythematosus (SLE)-associated thrombotic microangiopathy (TMA) based on their ADAMTS13 inhibitor profiles.

METHODS: The medical data of 31 SLE patients with clinically diagnosed TMA were analyzed. ADAMTS13 activity and ADAMTS13 inhibitor were measured in all patients.

RESULTS: TMA was attributable to active SLE in 19 patients. ADAMTS13 inhibitor and severe ADAMTS13 deficiency were detected in 6 of them. Patients with ADAMTS13 inhibitor (n = 6) exhibited a lower platelet count (7.3 ± 5.1 vs 25.0 ± 17.8 × 109 /l, p = 0.005) and more prevalent central nervous system (CNS) involvement (100.0% vs 23.1%, p = 0.003) than patients without ADAMTS13 inhibitor (n = 13). Patients with ADAMTS13 inhibitor also had mild renal involvement characterized by a higher estimated glomerular filtration rate (112.7 ± 18.0 vs 21.6 ± 12.0, p < 0.001), lower proteinuria level [0.6 (0.2-2.5) vs 8.1 (5.2-14.0) g/d, p = 0.011], and lower mean arterial pressure (95.3 ± 13.6 vs 117.5 ± 13.1 mmHg, p = 0.008) than was observed in patients without ADAMTS13 inhibitor. All patients with ADAMTS13 inhibitor achieved complete remission within 18.6 ± 8.7 days, while 3 patients (23.1%) without ADAMTS13 inhibitor achieved complete remission during a median followup of 5.0 months, even though more patients in this group received therapeutic apheresis (100.0% vs 50.0%, p = 0.021). The chance of complete remission increased by 10.8-fold (HR 10.8, 95% CI 1.8-65.5, p < 0.001) when ADAMTS13 inhibitor was present in SLE-associated TMA.

CONCLUSION: Acquired ADAMTS13 deficiency is associated with more severe thrombocytopenia and CNS involvement, mild renal involvement, rapid resolution, and relatively good treatment response in SLE-associated TMA.