Introduction: IgA nephropathy (IgAN) is the most common primary glomerulopathy worldwide. According to the Oxford Classification, changes in the kidney vascular compartment are not related with worse outcomes. This paper aims to assess the impact of thrombotic microangiopathy (TMA) in the outcomes of Brazilian patients with IgAN.
Materials and methods: Analysis of clinical data and kidney biopsy findings from patients with IgAN to assess the impact of TMA on renal outcomes.
Results: The majority of the 118 patients included were females (54.3%); mean age of 33 years (25;43); hypertension and hematuria were observed in 67.8% and 89.8%, respectively. Median creatinine: 1.45mg/dL; eGFR: 48.8ml/min/1.73m2; 24-hour proteinuria: 2.01g; low serum C3: 12.5%. Regarding to Oxford Classification: M1: 76.3%; E1: 35.6%; S1: 70.3%; T1/T2: 38.3%; C1/C2: 28.8%. Average follow-up: 65 months. Histologic evidence of TMA were detected in 21 (17.8%) patients and those ones presented more frequently hypertension (100% vs. 61%, p <0.0001), hematuria (100% vs 87.6%, p = 0.0001), worse creatinine levels (3.8 vs. 1.38 mg/dL, p = 0.0001), eGFR (18 vs. 60 ml/min/1.73m2), p = 0.0001), low serum C3 (28.5% vs. 10.4%, p = 0.003), lower hemoglobin levels (10.6 vs. 12.7g/dL, p<0.001) and platelet counts (207,000 vs. 267,000, p = 0.001). Biopsy findings of individuals with TMA revealed only greater proportions of E1 (68% vs. 32%, p = 0.002). Individuals with TMA were followed for less time (7 vs. 65 months, p<0.0001) since they progressed more frequently to chronic kidney disease (CKD) requiring kidney replacement therapy (KRT) (71.4% vs. 21,6%, p<0.0001). Male sex, T1/T2, and TMA were independently associated with progression to CKD-KRT.
Conclusions: In this study patients with TMA had worse clinical manifestations and outcomes. In terms of histologic evidence, E1 distinguished patients with TMA from other patients. Further studies are necessary to analyze the impact of vascular lesions on IgAN prognosis.