Background/Purpose:

In addition to glomerular lesion, renal vascular lesion is also an important prognostic marker of lupus nephritis (LN). Among various vascular changes thrombotic microangiopathy (TMA) presents with severe clinical manifestations and high mortality. The aim of this study was to assess the spectrum and impact of TMA on the outcomes of LN.

Methods: In this prospective observational study of one and half year duration, clinical and renal histopathological data of 102 patients with biopsy proven LN were noted and in addition evaluatation for antiphospholipid syndrome (APS) as cause of TMA in LN was also carried out. Study subjects were followed up actively for six months and various outcomes were noted. Cases were divided into two groups as LN with TMA and LN without TMA, and various features were compared between two groups.  Renal TMA was defined as intertubular artery and glomerular capillary response including endothelial cell swelling, lumen narrowing or obstruction & thrombi formation by light microscopy. Swelling of glomerular endothelial cells, detachment from glomerular basement membrane and widening of sub-endothelial space were identified by electron microscopy.   Outcomes noted were complete response, partial response, failure and death. 

Results: In the 102 patients with lupus nephritis, 26 patients were diagnosed as co-existing with renal TMA based on strict pathological criteria. Among the 26 patients three patients were found to have concomitant APS (11.5%). As compared to cases without TMA, patients with TMA had significantly higher rates of arthralgia, malar rash, advanced renal injury i.e. serum creatinine >3mg/dl(34.6% Vs 11.84% with P= 0.008), higher percentage of fibrocellular+fibrous crescents (P= 0.018) and tubular atrophy (P= 0.006),. Even though the rates of endocapillary proliferation (73.1% Vs 56.5%), hyaline thrombhi(19.2% Vs 7.9%), and glomerular sclerosis(46.2% Vs 30.3%) were higher in TMA group compared to cases without TMA, but failed achieve statistical significance.. Patients of Lupus nephritis with TMA had poorer outcomes i.e higher rates of failure to treatment(P=0.011) and lower rates of complete response(P=0.031) compared to non TMA group. Renal TMA group is significantly associated with 7.26 times more likely poor outcomes than non TMA group(Odds ratio7.262, 95% confidence interval:1.585 to 31.303, P= 0.008).

Conclusion: Presence of TMA in lupus nephritis is associated with adverse clinicopathological presentation and poorer outcome.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/effect-of-thrombotic-microangiopathy-on-clinical-outcomes-in-lupus-nephritis/