Difference in thrombotic microangiopathy between concurrently and previously diagnosed systemic lupus erythematosus

Thrombotic microangiopathy (TMA) syndromes are potentially life-threatening complications and are defined as integrated syndromes of microangiopathic hemolytic anemia, thrombocytopenia, and organ injury. Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect various organs, including the hematopoietic system. SLE can complicate with TMA and can be categorized into two distinct groups by chronological association: TMA occurring as the initial presentation and leading to a diagnosis of SLE concurrently (TMA-cSLE) or TMA developing in patients previously diagnosed as having SLE (TMA-pSLE). We examined the differences in clinical characteristics, treatment responses, and clinical outcomes between these groups.

We reviewed data of patients diagnosed as having TMA and SLE at Taipei Veterans General Hospital between 2002 and 2013. We included 29 patients: 8 and 21 in TMA-cSLE and TMA-pSLE groups, respectively. All underwent plasma exchange. Patients' demographic and clinical characteristics, disease activity, and treatment modality were summarized.

Overall survival (OS) from SLE or TMA diagnosis was poor for the TMA-cSLE group. Median OS from SLE diagnosis was 2.9 months in the TMA-cSLE group and 103.5 months in the TMA-pSLE group (p < 0.001). Median OS from TMA diagnosis was 2.9 months in the TMA-cSLE group and 10.7 months in the TMA-pSLE group (p = 0.58). Time to TMA remission after treatment appeared longer in the TMA-cSLE group (38.00 vs 10.76 days). Multivariate Cox analysis revealed TMA-cSLE and anti-RNP positivity were independent risk factors for mortality in SLE patients with TMA.

The occurrence of TMA with SLE is rare, and its vigorous course results in high mortality and morbidity rates. In patients without a history of autoimmune disease, early suspicion of TMA and working-up for SLE under this condition are vital. Early recognition of TMA-cSLE and prompt plasma exchange with upfront immunosuppressive therapies for TMA-cSLE patients or anti-RNP-positive patients may improve their prognosis.