Increasing Incidence of Inadequate Kidney Biopsy Samples Over Time: A 16-Year Retrospective Analysis From a Large National Renal Biopsy Laboratory

Abstract

Introduction: Renal biopsy remains an essential tool for the diagnosis and treatment of patients with medical kidney disease. Recently, there has been a perceived change in the number of inadequate samples. The aim of this study was to determine the native renal biopsy miss rate from 2005 to 2020 at Arkana Laboratories, a nationwide kidney biopsy service.

Methods: From 2005 to 2020, a total of 123,372 native kidney biopsies were received from >2500 nephrologists practicing across 44 US states. The miss rate was determined by age and year. In a subset of biopsies received in 2005 and 2018, the biopsy operator was determined, nephrologist or radiologist. Furthermore, the miss rate, needle gauge, biopsy depth by operator, and biopsy core width by gauge were measured.

Results: The miss rate increased markedly from 2% in 2005 to 14% in 2020. Radiologists performed 5% of biopsies in 2005 and 95% in 2018 using smaller diameter (18g/20g) needles 92% of the time. Glomeruli per centimeter of core biopsy and mean core width were significantly lower with smaller needles. The miss rate deep was significantly lower for nephrologists and remained consistent within operator between the 2 time points. The miss rate did not correlate with the increasing age of the population who had biopsies.

Conclusion: This increase in kidney biopsy miss rate significantly affects patient care in the management of medical kidney disease. Its correlation with the complete reversal in operators suggests an urgent need for interaction with and training of radiologists in this critical technique.

Keywords: interventional nephrology; interventional radiology; medical renal disease; percutaneous renal biopsy.

Graphical abstract

Figure 1

Native renal biopsies (bars) referred by individual nephrologists (line) across the United States over time.

Figure 2

Miss rate over time determined by report review with the trend line in red (Cochran-Armitage trend test: Z = −26.20, P < 0.001).

Figure 3

Native renal biopsies by age over time. The data are expressed as percentage biopsies by age group per year. There is a significant increase over time of patients aged >60 years. Comparing 2005 and 2018, there is an older population driven primarily by the almost 10% increase in patients aged 60 to 79 years (Cochran-Mantel-Haenszel χ² (1) = 82.50, P < 0.001). Bx, biopsy.

Figure 4

Number of glomeruli/cm biopsy core by needle gauge. The data are expressed as the median (middle line) in a box bounded by the IQR 25%–75%, the mean (x), and the min and max lines. 14g—med 25.0, mean 25.1, IQR 14.8–33.2, min/max 11.0–52.5, n—25; 16g—med 10.6, mean 12.3, IQR 7.6–17.5, min/max 6.2–23.3, n—40; 18g—med 9.4, mean 9.8, IQR 7.7–11.7, min/max 5.9–14.4, n—185; 20g—med 1.8, mean 2.1, IQR 1.3–2.7, min/max 0.1–4.6, n—20. In pairwise comparisons from a one-way analysis of variance, the mean number of glomeruli/cm from each needle gauge is significantly different from all other means; all P < 0.01 controlling for multiple comparisons. #, number; IQR, interquartile range; max, maximum; min, minimum.

Figure 5

Width of renal core by needle gauge. (a) Box plot of tissue width in microns. Box bounded by first and third quartiles, center bar = median, x = mean, whiskers = minimum and maximum values, circle = outlier (mean ± SEM: 14g—894 ± 20.0, 16g—563 ± 10.1, 18g—303 ± 29.0, 20g—155 ± 22.5). Pearson’s correlation between needle gauge and tissue width: r = −0.91, 95% CI [−0.94 to −0.87]. (b) Representative photomicrographs of renal cores obtained with different needle gauges revealing example relative widths: 14g—888 μm, 16g—565 μm, 18g—325 μm, and 20g—174 μm. Note that the 20g core is less than the mean width of the glomerulus. Tissue compression followed by decompression during the procedure allowed the single glomerulus to be obtained (original magnification ×100; the bars on either side of each micrograph represent the photographic field of view).