Centers With Higher Volume of Peripheral Endovascular Procedures Have Better Results

Hospitals performing a higher annual volume of lower-extremity endovascular interventions have better in-hospital outcomes, fewer complications, and lower hospitalization costs than those with lower volumes, according to a study published online June 3, 2015, ahead of print in the American Journal of Cardiology.

“We recommend further studies to investigate this hospital volume-outcome relationship from other databases,” study author Apurva O. Badheka, MD , of Yale-New Haven Medical Center (New Haven, CT), told TCTMD in an email. “Although volume is not the sole metric of quality, it is albeit an important one.”

Using data from the Nationwide Inpatient Sample, the researchers studied 92,714 adult patients (54.8% men) with peripheral vascular disease who underwent an endovascular intervention between 2006 and 2011. More than half of procedures (54.42%) were elective. Hospitals were divided into quartiles according to annual procedure volume, ranging from a low of ≤ 36 to a high of > 126.

Rates of in-hospital mortality (primary outcome), complications, amputations, and the composite of in-hospital mortality and complications were all elevated in the lowest-volume compared with the highest-volume centers (table 1).

Multivariate analysis revealed several predictors of greater in-hospital mortality: age, female sex, greater comorbidity burden (score ≥ 2 on the Charlson/Deyo comorbidity index), emergent/urgent admissions, and weekend admissions (table 2).

On multivariate analysis, greater hospital procedure volume—comparing the highest quartile with the lowest—was associated with lower odds of in-hospital mortality (OR 0.65; 95% CI 0.52-0.82), the composite of in-hospital mortality and complications (OR 0.85; 95% CI 0.73-0.97), and amputation (OR 0.52; 95% CI 0.45-0.61).

Overall hospitalization cost also was lower in the highest-volume vs the lowest-volume centers ($18,123 vs $23,495), a difference that remained after multivariate adjustment.

Competency Guidelines Need to Change?

Although prior studies have shown associations between hospital procedure volume and outcomes from specific endovascular procedures, “our study adds to the literature by showing a strong inverse relationship between hospital volume and mortality/postprocedural complications following all lower-extremity peripheral endovascular interventions that included both angioplasty and stenting,” the authors write. “This is important since hospital volume is considered an important proxy for quality in most procedures.”

They point out that competency guidelines from the American College of Cardiology, American Heart Association, and Society for Cardiovascular Angiography and Interventions address the operator volume required to maintain expertise (> 25 annual procedures) but not institutional volume.

“The competency guidelines perhaps need to be revised to include hospital volume as one of the quality metrics,” Dr. Badheka said in his email to TCTMD.

In correspondence submitted to the journal in response to the study, however, Shikhar Agarwal, MD, MPH, and Karan Sud, MD, of the Cleveland Clinic (Cleveland, OH), urge caution in interpreting the results, saying that “one would certainly express reservations about using an inpatient database for assessment of hospital volumes in lower-extremity endovascular interventions,” which do not always require hospitalization.

They note that a prior study showed that 65% of endovascular procedures in men and 61% in women in 2009 were performed in the outpatient setting.

“Although one would believe that major complications like bleeding or need for amputation would require inpatient hospitalization, exclusion of a large number of low-risk procedures (that were discharged on the same day) from the denominator would lead to a marked overestimation of these estimates,” Drs. Agarwal and Sud write.

Thus, the question about the relationship between hospital procedure volume and outcomes “is only partly answered by use of this dataset in isolation,” they comment. “Perhaps utilization of more robust databases, which provide insight into real-world outpatient surgical procedures, would provide more truthful and more complete insight into this important question.”

Responding to the letter, Dr. Badheka pointed out that the figures cited by Drs. Agarwal and Sud related to procedures for intermittent claudication only, adding that the same study showed that critical limb ischemia procedures were 2.7 times more likely to be performed in the inpatient setting.

“Our study evaluated critical outcomes like in-hospital mortality, amputation rates, and complications, which are more likely to occur in patients with critical limb ischemia rather than those undergoing elective procedures for intermittent claudication,” Dr. Badheka said. “We… encourage other authors to investigate volume-outcome relationships for outpatient procedures and see if they differ from our results.”

1. Arora S, Panaich SS, Patel N, et al. Impact of hospital volume on outcomes of lower extremity endovascular interventions (insights from the Nationwide Inpatient Sample [2006-2011]). Am J Cardiol. 2015;Epub ahead of print.
2. Agarwal S, Sud K. Impact of hospital volume on outcomes of lower extremity interventions: only half the story [letter]. Am J Cardiol. 2015;Epub ahead of print.

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