In patients with systemic lupus erythematosus (SLE)-associated thrombotic microangiopathy (TMA), acquired ADAMTS13 deficiency is linked to more severe thrombocytopenia and central nervous system (CNS) involvement, mild renal involvement, rapid resolution, and a relatively good treatment response, according to data published in The Journal of Rheumatology.
The investigators sought to examine the clinical characteristics and outcomes of subgroups of patients with SLE-TMA with and without acquired ADAMTS13 deficiency. The medical data of 31 patients with clinically diagnosed TMA were analyzed, and ADAMTS13 inhibitor and ADAMTS13 activity were measured.
TMA was attributable to active SLE in 19 individuals, and ADAMTS13 inhibitor and severe ADAMTS13 deficiency was detected in 6 patients. Participants with ADAMTS13 inhibitor exhibited significantly lower platelet counts (7.3 ± 5.1 x 109/L vs 25.0 ± 17.8 x 109/L; P =.005) and higher hemoglobin levels (62.8 ± 8.0 g/L vs 51.3 ± 11.8 g/L; P =.046) compared with patients without ADAMTS13 inhibitor.
Patients with ADAMTS13 inhibitor had significantly more prevalent CNS involvement compared with those without ADAMTS13 inhibitor (100% vs 23.1%, respectively; P =.003). Moreover, patients with ADAMTS13 inhibitor also exhibited mild renal involvement, which was characterized by higher estimated glomerular filtration rates (112.7 ± 18.0 vs 21.6 ± 12.0; P <.001), lower proteinuria levels (0.6 g/d vs 8.1 g/d; P =.011), and lower mean arterial pressure (95.3 ± 13.6 mm Hg vs 117.5 ± 13.1 mm Hg; P =.008) compared with patients without ADAMTS13 inhibitor.
Patients without ADAMTS13 inhibitor had significantly longer hospitalizations (45.1 ± 13.4 days vs 30.5 ± 3.4 days; P =.005). When the ADAMTS13 inhibitor was present, the likelihood of complete remission and partial remission were increased (hazard ratio [HR], 10.8; 95% CI, 1.8-65.5; P <.001; and HR, 6.9; 95% CI, 1.3-37.4; P <.001, respectively).
The investigators concluded that the study had several limitations, including a small sample size. Furthermore, complement factors, inhibitors, and potential genetic defects were not assayed in most of the participants, despite the potential pathogenetic effect of complement activation in those with SLE-TMA and normal ADAMTS13 activity.
Yue C, Su J, Gao R, Wen Y, et al. Characteristics and outcomes of patients with systemic lupus erythematosus-associated thrombotic microangiopathy, and their acquired ADAMTS13 inhibitor profiles [published online July 15, 2018]. J Rheumatol. doi:10.3899/jrheum.170811