Assessing Evidence Quality for Endovascular Arteriovenous Fistulas.

To the Editor:

We read the article by Malik et al with great interest; however, we have 2 concerns about their conclusion that states that percutaneous arteriovenous fistulas (AVFs) can be used safely in place of surgical AVFs.

First, the authors may not have incorporated all relevant studies that compared the complications between percutaneous and surgical AVFs. Indeed, we found other studies, in addition to the included studies. The results of meta-analyses may be biased because of the lack of a comprehensive literature search.

Second, they may overstate their conclusions given the large uncertainty of the evidence. Malik et al concluded that percutaneous AVF is a unique and safe alternative with outcomes comparable to surgical AVF; however, we challenge this claim by arguing that the wide 95% confidence intervals indicate the imprecision of the estimates. According to the Grading of Recommendations Assessment, Development and Evaluation guidelines, we evaluated the certainty of evidence for complications as very low because the included studies had small sample sizes and a serious risk of bias, mainly because of confounding. We suggest that the authors moderate their conclusions by acknowledging that the evidence is very uncertain about the effect of percutaneous AVF on complications. Additionally, given the fact that 1 of the authors had financial conflicts of interest with Medtronic, a manufacturer of the Ellipsys Vascular Access System, we would appreciate a careful discussion of the results. Notably, a prior study reported that systematic reviews with financial conflicts of interest are associated with misrepresentation of conclusions.