Endovascular Techniques Increasingly Common in Surgical Domain

Lara C. Pullen, PhD

April 14, 2011

April 14, 2011 (Chicago, Illinois) — Transcatheter embolization (TCE) for the treatment of acquired arteriovenous fistulas (aAVF) yields rates of in-hospital mortality, aggregate morbidity, and length of stay similar to those seen with surgical clipping.

Premal Trivedi, a medical student at Georgetown University in Washington, DC, presented a retrospective analysis of data from the Nationwide Inpatient Sample (2001 to 2008) here at the Society of Interventional Radiology 36th Annual Scientific Meeting. The Nationwide Inpatient Sample contains data on hospitalizations from community, academic, rural, and urban hospitals in 42 states.

The study was designed by Mr. Trivedi and his colleague to analyze national trends in technique use and to compare in-hospital outcomes of TCE with outcomes from surgical clipping in the treatment of aAVF. Mr. Trivedi discussed the research with Medscape Medical News and explained that there is almost no information comparing the use of the 2 techniques.

The analysis looked at 6625 aAVFs, 850 (12%) of which were treated with TCE. The researchers found that national use of embolization increased 20-fold from 2001 to 2008 (from 1.9% to 25.2%; P < .01).

Embolizations were most likely to occur in teaching hospitals. Specifically, the researchers identified 2 independent predictors of embolization: admittance to a teaching hospital (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.4 to 3.0; P < .05) and age younger than 60 years (OR, 1.4; 95% CI, 1.2 to 2.0; < .05). In contrast, comorbid vascular disease (OR, 2.9; 95% CI, 1.1 to 7.2; P < .05) and peripheral vascular disease (OR, 1.7; 95% CI, 1.1 to 2.5; P < .05) were independent predictors of surgical clipping. He explained that if you look at the types of patients undergoing each procedure, they tend to be distinct subsets of patients. Moreover, comorbidities are expected to differ between the 2 populations.

Patients undergoing TCE had an increased incidence of postoperative hemorrhage, compared with patients undergoing surgical clipping (12.7% vs 1.4%; P < .05). The study was not designed, however, to provide detail on the degree of hemorrhage. There was no difference between TCE and surgical clipping in in-hospital mortality (1.9% vs 1.5%; P = .71) or aggregate morbidity (21.6% vs 18.5%; P = .38). However, compared with TCE, surgical clipping had a higher rate of peripheral vascular complications (5.3% vs 12.0%; P < .05).

Mr. Trivedi noted that there were many limitations to the study. In particular, although the median total hospitalization charges were higher with TCE than surgical clipping ($50,812 vs $27,593; P < .01), the researchers were not able to identify what contributed to the increased cost. He did note that the median length of stay was similar between the 2 procedures (5 days for TCE vs 4 days for surgical clipping; P = .08), and therefore unlikely to have contributed significantly to the difference in cost.

Discussing the paper with Medscape Medical News, Robert L. Vogelzang, MD, from the Department of Radiology in Northwestern Memorial Hospital, Chicago, Illinois, explained that he believes the difference in cost is a result of the sophisticated catheters, wires, and advanced medical devices that are used during TCE, which are more expensive than the surgical supplies required for clipping.

Mr. Trivedi explained to Medscape Medical News that the study "is a good foundation to further explore what is going on." Our results provide a snapshot of what is happening in hospitals across the country, but the study was not designed to answer why these things are happening, he said.

Dr. Vogelzang agreed, saying that "the paper is interesting, but it doesn't tell the whole tale." He notes that although the data describe the increased use of TCE, they do not describe what type of fistulas are being treated.

As did Mr. Trivedi, he found himself wishing that he knew more about the actual populations being treated: "[The authors] are relying on coding, and coding is notoriously unclear," he said. The use of coding creates a big basket that includes many different types of fistulas. Nonetheless, this report describes a paradigm shift in the use of endovascular techniques, Dr. Vogelzang noted.

Mr. Trivedi and Dr. Vogelzang have disclosed no relevant financial relationships.

Society of Interventional Radiology (SIR) 36th Annual Scientific Meeting: Abstract 217. Presented March 30, 2011.