Clinicopathological characteristics and prognosis of non-hypertensive IgA nephropathy patients with microangiopathy lesions

Objective To evaluate the clinicopathological characteristics and prognosis of IgA nephropathy (IgAN) patients with microangiopathy lesions and with no hypertension. Methods Adult IgAN patients without hypertension were selected from Peking University First Hospital. All kidney biopsies were independently reviewed by 2 investigators. Patients were divided into three groups (microangiopathy group, simple arterio/arteriolosclerosis group and normal vascular group) by renal arteriolar lesions. Composite kidney end point event defined as a ≥30% reduction in estimated glomerular filtration rate (eGFR) and end-stage kidney disease. Cox regression analysis was used to test the association between microangiopathy lesions and the outcomes. Results A total of 420 patients were included in this study, of which 37(8.8%) patients had renal arteriolar microangiopathy lesions, 134 (31.9%) patients had simple arterio/ arteriolosclerosis, and the others had no vascular lesion. Compared with simple arterio/arteriolosclerosis group or non-vascular lesion group, patients with renal arteriolar microangiopathy lesions had more severe urine protein (P=0.002), worse renal function (P<0.001), higher proportion of segmental glomerulosclerosis and/or balloon adhesion (S1), tubular atrophy/interstitial fibrosis (T1/2), cellular/fibrocellular crescents (C1/2) (all P<0.05). During the follow-up, 20(54.1%) patients with microangiopathy lesions, 45(33.6%) patients with simple arterio/arteriolosclerosis and 82(32.9%) patients without vascular lesion reached the composite kidney end points (χ2=6.491, P=0.039). In a multivariable Cox regression model, the presence of microangiopathy lesions was an independent risk factor for kidney disease progression in IgAN patients (HR=1.872, 95%CI 1.044-3.357, P=0.035), and simple arterio/arteriolosclerosis was not a risk factor for kidney disease progression. Conclusion It is not uncommon for non-hypertensive patients with IgAN having microangiopathy lesions, which suggests that hypertension is not the sole risk factor for microangiopathy lesions. Key words: Glomerulonephritis, IgA; Renal artery; Prognosis; Microangiopathy lesions; Renal pathology