Complement-amplified thrombotic microangiopathy in systemic lupus erythematosus and lupus nephritis: a systematic...

Thrombotic microangiopathy (TMA) complicating systemic lupus erythematosus (SLE) and lupus nephritis (LN) spans immune thrombotic thrombocytopenic purpura, anti-phospholipid-associated microangiopathy, secondary endothelial injury, and complement-amplified/atypical hemolytic uremic syndrome (aHUS)-like phenotypes. The boundaries remain uncertain, and treatment evidence is dominated by selectively published cases.

In this PROSPERO-registered systematic review (CRD420261409684), we searched PubMed, Embase, and Web of Science through to 17 March 2026, verified the source identity and eligibility, and performed a PubMed-only update through to 14 August 2026. We reconstructed patient-level reports by phenotype, competing mechanisms, complement-related evidence, treatment, and outcome. We included citable published abstracts when patient-level data were extractable but analyzed them as a lower-information stratum rather than as equivalent to full texts. Analyses were descriptive. We did not include China National Knowledge Infrastructure (CNKI) because no verifiable search record was available. One reviewer performed the screening, extraction, and appraisal. We report both as protocol deviations.

We included 56 sources describing 78 patients: in total, 39 full-text sources/61 patients and 17 published abstract sources/17 patients. There were 56 female patients (71.8%), and the median age was 24.5 years. Source-adjudicated microangiopathic hemolysis, thrombocytopenia, acute kidney injury/renal failure, strict TMA identified on kidney biopsy, and dialysis/renal replacement therapy (RRT) were present in 71 (91.0%), 74 (94.9%), 67 (85.9%), 42 (53.8%), and 46 (59.0%), respectively. Low C3/C4 levels were reported in 55 (70.5%), strict T2 complement evidence in 1 (1.3%), and index event terminal/tissue activation in 6 (7.7%). Complement inhibitors were reported in 60 (76.9%) and renal and hematologic improvements in 49 (62.8%) and 65 (83.3%), respectively. Certainty was very low, and treatment comparisons were not estimable.

SLE/LN-associated TMA is heterogeneous, and complement may act as a driver, an amplifier, or an epiphenomenon. Case-based evidence supports rigorous mechanistic adjudication and biomarker-rich registries, but cannot establish incidence, prognosis, comparative efficacy, or universal treatment duration.

https://www.crd.york.ac.uk/PROSPERO/view/CRD420261409684, identifier CRD420261409684.