Clinical characteristics and treatment response of patients with SLE complicated with thrombotic thrombocytopenic purpura.

BACKGROUND: SLE complicated with thrombotic thrombocytopenic purpura (SLE-TTP) is a rare but potentially fatal condition. Current studies regarding SLE-TTP are limited to case reports and literature reviews. This study presents a cohort of patients with SLE-TTP and aims to investigate their clinical characteristics and treatment outcomes, as well as to explore the efficacy of rituximab (RTX) maintenance therapy (RMT) for relapse prevention and long-term disease control. METHODS: Patients with SLE-TTP were retrospectively identified in an SLE cohort. Baseline characteristics, acute-phase treatment responses and long-term outcomes were collected. All patients received RTX-containing induction therapy during the acute phase of TTP. Maintenance therapy was categorised as RMT (regular RTX infusions) or non-RMT (conventional immunosuppressants and/or biologics) regimens. TTP relapse, lupus low disease activity state (LLDAS) and infection rates were compared between groups. RESULTS: Of 33 patients with SLE-TTP, 31 (94%) achieved clinical remission following RTX-containing induction therapy, while 2 died during the acute phase. Fourteen patients (45%) received RMT, and 17 (55%) received non-RMT regimens. During a median follow-up of 22.9 months, TTP relapse occurred in seven (23%) patients: one (7%) in the RMT group and six (35%) in the non-RMT group. Kaplan-Meier analysis revealed significantly longer relapse-free survival with RMT (log-rank p=0.027). All patients receiving RMT achieved LLDAS, compared with 59% of patients in the non-RMT group. Infection rates were comparable between the two groups. CONCLUSIONS: RTX-containing induction regimens resulted in high rates of clinical remission in patients with SLE-TTP. RMT was associated with a significantly reduced risk of TTP relapse and superior long-term control of SLE disease activity, without an excess risk of severe infection. These findings support RMT as a potential option for long-term management of SLE-TTP.