Plasma ADAMTS-13 activity was negatively associated with total pathological AI scores ( r = -0.326, p < 0.001), endocapillary hypercellularity ( r = -0.419, p < 0.001), cellular crescents ( r = -0.274, p < 0.001), subendothelial hyaline deposits ( r = -0.266, p = 0.001), interstitial inflammatory cell infiltration ( r = -0.304, P < 0.001), tubular atrophy ( r = -0.199, p = 0.011), acute glomerular vascular lesions ( r = -0.344, p < 0.001) and acute renal vascular lesions ( r = -0.338, p < 0.001).