In a recent article published in the American Journal of Kidney Diseases, Corapi et al present a meta-analysis of bleeding complications when performing a kidney biopsy. Corresponding author Dr. Craig Gordon (CG), from Boston University Medical Center, spoke with Dr. Kenar Jhaveri (eAJKD), eAJKD Blog Editor, about this study. This is the first part of the interview; the second will post later in the week.
eAJKD: Can you summarize the findings of your study?
CG: We reviewed the literature on bleeding complications (macroscopic hematuria and transfusion requirements) after a kidney biopsy from 1980 through June 2011 using real time ultrasound techniques. We found that the rate of macroscopic hematuria was 3.5%, and the rate of packed red cell transfusion was around 0.9%. Factors that led to increased transfusion requirements were larger needle gauge, a mean serum creatinine >2 mg/dL, and acute kidney injury. Women had a statistically higher risk of transfusion requirements. For hematuria, we didn’t find any statistically significant predictors, but we found the same direction of effect.
eAJKD: Were you surprised by your findings?
CG: What we normally think are risk factors, such as elevated coagulation profiles and low platelets, are all individual patient risk factors. I think anytime one looks at study-level data, one is unlikely to see those individual patient factors. Number of needle passes, the one factor that has been reported in prior studies, didn’t predict either of the hemorrhagic outcomes. I think a caveat there is that the needle gauge and the number of passes are inversely related. So perhaps if we were able to look at the analysis with both factors, we could have found a relationship.
eAJKD: How come hypertension was not a significant factor in predicting bleeding after kidney biopsies?
CG: It did not reach statistical significance. In studies with a mean systolic pressure over 130 mmHg, the rate of transfusion was 1.4%. In studies with a lower mean systolic pressure, it was around 1%, but the P value was 0.09.
eAJKD: Do certain underlying kidney diseases or indications for biopsy tend to bleed more than others? Was any disease-specific data available from your evaluation?
CG: We used evidence of nephrotic syndrome as a marker for glomerular diseases, and weren’t able to find a strong relationship. One of the studies compared patients with amyloidosis to those without amyloidosis and didn’t find a difference in complication rates. Most of the other studies didn’t report a lot of information on the complication rate with the biopsy finding. It would be nice to be able to stratify and say, “These are people you need to be worried about, and these are ones you don’t need to worry as much about.”