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 × 10/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.