In the second of two parts, Dr. Gordon (CG), from Boston University Medical Center, continues to discuss his recent meta-analysis on bleeding complications when performing a kidney biopsy with Dr. Kenar Jhaveri (eAJKD), eAJKD Blog Editor. For the first part of this interview, please check out the previous post.
eAJKD: Why do you think women had a higher rate of bleeding?
CG: The fact that women had higher risk of bleeding was most surprising for us. Other organ biopsy literature also noted an increased bleeding risk in women. For the same creatinine level, a woman is going to have a lower glomerular filtration rate (GFR) than a man. Smaller kidney size, deeper penetrations of the needle, and/or lower GFR are my postulations regarding why this might have happened.
eAJKD: Is higher or lower body mass index (BMI) associated with increased risk of bleeding?
CG: There was almost no data on BMI. The later studies included in the meta-analysis did have some information on BMI, but most of them did not. Because BMI is a patient-level factor, we weren’t able to do much with it. In our discussion, we highlight this is an important piece of information to include in future studies. But It’s hard to know if low BMI or high BMI could be a risk factor, or maybe it’s a U-shaped curve.
eAJKD: Manno et al showed desmopressin acetate (also known as 1-deamino-8-d-arginine vasopressin [DDAVP]) use decreased risk of bleeding without significant cost increase. Any comments on that paper and how that could change the way we perform kidney biopsies?
CG: It’s a very important paper for two reasons. One, is it’s the only randomized trial that I’m aware of in this area, and, two, it’s the only one that directly looked at desmopressin acetate. The flipside though is that patients who were administered desmopressin acetate had relatively normal kidney function; the mean creatinine level was 1 mg/dL. It is vastly different from what most of us would use in clinical practice as far as indications for desmopressin acetate.
This study looked at hematoma, proportion with hematoma, and size of hematoma as the outcome measure. We struggled with that outcome because if you included only studies that routinely did ultrasound, we saw different rates of hematomas than in studies that just did an ultrasound when there were symptoms. In addition, we felt clinical outcomes such as hematuria or need for transfusions were more important. The editorial that went along with the manuscript suggested that the clinical outcomes of hematuria and transfusion were not different in the two arms.
eAJKD: Was there any difference in outcomes when biopsies were done by nephrologists versus radiologists?
CG: There was no difference. I do believe the ultrasound guidance and the spring-loaded biopsy devices probably do make it safer. And I think if you’re careful in your selection criteria and you have an operator who’s relatively experienced, probably the complication rates are going to be similar (nephrology or radiology). If you had 20,000 biopsies done by radiologists and 20,000 by nephrologists, maybe there might be a difference, but unlikely significant. Nevertheless, I think for many other important reasons, it’s a procedure that ought to be done by a nephrologist. Nephrologists know how many passes are appropriate to get an adequate yield. But, I don’t think the radiologists do an inferior job from the standpoint of complications.
eAJKD: Any thoughts on computed tomography–guided kidney biopsies?
CG: We restricted our data analysis to ultrasound-guided kidney biopsies. There’s actually very little published in the field of computed tomography–guided kidney biopsies to make any significant comment. There is a small amount of literature on transjugular biopsies of the kidney in people with cirrhosis. We excluded those, but I think that’s another interesting area to see if there is a difference in the safety when compared to the traditional transcutaneous approach.