Kidney Biopsy Safety and Adequacy in Patients with Obesity

Obesity is associated with risk for complications related to kidney biopsy. Long Qian, MD, and colleagues conducted an analysis to compare the safety and adequacy of kidney-biopsy procedures between obese and nonobese patients.

Results were reported during a poster session at the American Society of Nephrology Kidney Week 2022. The poster was titled Safety and Adequacy of Kidney Biopsy Procedure in Patients With Obesity.

The analysis included data from patients in the Yale University kidney biopsy cohort enrolled between 2015 and 2017. Following adjustment for prebiopsy risk factors and needle gauge, linear regression analysis was used to examine the association between class 2 obesity (defined as body mass index ≥35 kg/m²) with postbiopsy drop in hematocrit and with the number of glomeruli sampled. A supplementary analysis using data from Johns Hopkins University was also performed.

The Yale cohort included 337 patients, and of those, 23% (n=76) had obesity. Patients with obesity were more likely to undergo biopsy using an 18-gauge needle (vs 16-gauge needle) compared with nonobese patients (66% [n=48] vs 45% [n=113]; P=.002). In univariable analysis, patients with obesity had a lesser drop in hematocrit from pre- to postbiopsy (2.1% vs 3.0%; unadjusted difference, –0.95%; 95% CI, –0.14% to –1.75%). Following adjustment for prebiopsy factors, the difference was –0.92% (95% CI, –1.73% to –0.11%). There was no association between obesity and drop in hematocrit following further adjustment for needle gauge. Fewer glomeruli were sampled from patients with obesity.

The Johns Hopkins cohort included 78 patients, and of those, 12 were obese. All biopsies at Johns Hopkins were performed using an 18-gauge needle. There was no association between obesity and drop in hematocrit. Results of meta-analyses of the two cohorts found no association between obesity and drop in hematocrit.

In conclusion, the researchers said, “Obese patients did not have a greater risk of postbiopsy hematocrit drop than those without obesity but tended to have fewer glomeruli available for diagnosis. Future studies could examine techniques to improve diagnostic yield of kidney biopsy for obese patients.”

Source: Qian L, Weinstein JN, Melchinger HC, et al. Safety and adequacy of kidney biopsy procedure in patients with obesity. TH-PO564. Abstract of a poster presented at the American Society of Nephrology Kidney Week 2022; November 3, 2022; Orlando, Florida.