Risk Factors and Timing of Native Kidney Biopsy Complications

Background: The appropriate observation period, rate and risk factors of complications after a percutaneous renal biopsy remain debated. Methods: We retrospectively studied native kidney biopsies performed in our institution between January 2007 and July 2011. Outpatients had either an 8- (67%) or a 24-hour (33%) observation period. Results: 312 biopsies were reviewed (287 patients), 51% of patients were female and the mean age was 54 ± 15 years. Half of these biopsies were performed in outpatients. A total of 15% of patients developed a symptomatic hematoma, 9% received a red blood cell transfusion and 1% required an angio-intervention. Eighty-four percent of the complications manifested within the first 8 h, 86% at 12 h and 94% at 24 h. Outpatients experienced significantly less complications, all manifesting within the first 8 h, 14% required an observation period longer than planned. The risk of symptomatic hematoma increased to 11, 20, 35 and 40% in patients with >200, 140-200, 100-140 and 9/l platelets, respectively (p = 0.002). It also increased in hemodialysis patients (29% compared to 14%, p = 0.02). We found no association of risk with the number of biopsy passes and only a trend with needle size. Conclusion: Symptomatic hematomas occurred in 15% of kidney biopsies and were strongly associated with platelet count and hemodialysis. Outpatients experienced fewer complications; therefore, we can conclude that same-day discharge in selected patients is safe

Estimating the Change in Renal Function During the First Year of Therapy in ANCA-Associated Vasculitis

Introduction: Studies in antineutrophil cytoplasmic autoantibody (ANCA)–associated vasculitis (AAV) consistently show that the months following diagnosis have the greatest impact on the long-term renal function. Yet, it remains uncertain how much early gain should be expected with treatment. We sought to determine the factors associated with the change in glomerular filtration rate (GFR) throughout the first year. Methods: We retrospectively reviewed patients from 3 university hospitals who received treatments. We assessed the proportions of glomeruli with crescents, with global sclerosis, the AAV glomerulonephritis classification, the severity of chronic vascular and tubulo-interstitial disease, and the presence of acute tubular injury (ATI). We used repeated-measures analyses of variance (ANOVAs) to determine factors associated with the change in GFR throughout the first year. Results: There were 162 individuals with AAV identified, 96 with a valid renal biopsy and 82 with at least 12 months of follow-up. The initial GFR of 30 ± 25 ml/min per 1.73 m2 rose by 15 ± 20 during the first year. The severity of pathology findings, myeloperoxidase positivity, and those with kidney- and lung-limited disease presented with a lower GFR. Younger patients with a lower initial GFR and the presence of ATI correlated with a greater increase in GFR by 12 months. A higher proportion of crescents did not predict the change in GFR, contrary to global glomerulosclerosis, where each 10% increase added a loss of 2.7 ± 1.3 ml/min per 1.73 m2 per year (P = 0.03). These factors remained independent of each other. Conclusion: Multiple factors influence renal recovery during the first year of therapy. Estimating the change in GFR early on will help identify and reassess outliers. Keywords: ANCA-associated vasculitis, crescentic glomerulonephritis, immunosuppression, patholog