Less volume, more mortality: should we be concerned?

Courtesy of Dr. Agustín Vecchia.

In general, guidelines recommend a number of procedures a year for operators to maintain a reasonably safe level of proficiency. Even though this number is arbitrary and operators’ aptitude varies considerable, more than one publication has found an inverse correlation between procedure volume and outcomes.

This study incorporated 10,496 operators form the National Cardiovascular Data Registry with a total 3,747,866 PCIs and divided them according to volume into: low (<50 PCIs a year), intermediate volume (50 to 100 PCIs a year), and high volume (>100 PCIs a year). Each group was adjusted for inhospital outcomes and mortality.

Annual PCI median for the whole group was 59; 44% of operators performed less than 50 procedures a year. Low volume operators that also worked in low volume hospitals, more frequently performed emergency procedures and primary PCIs than those in higher volume hospitals. Unadjusted inhospital death was 1.86% for low volume operators, 1.73% for medium volume operators and 1.48% for high volume operators. Adjusted inhospital mortality risk was higher in procedures done by low and intermediate risk operators (adjusted OR for low vs. high: 1.16; adjusted OR for intermediate vs. high: 1.05), as was the risk of new dialysis post PCI. There were no differences in bleeding.

Authors have concluded that many operators in the US are doing less procedures than the number the guidelines recommend and, despite the small differences in absolute risk, and that they could be explained by unmeasured variables, there still is an inverse correlation between operator volume and inhospital death that persists despite adjusted risk analysis.

Editorial Comment

The present work on a large population studied between 2009 and 2015 presents interesting data that exceed the extent of this comment, but are worth reading in the original study; for example the low rate of transradial approach, the fact that more than one fourth of patients were treated with bare metal stents, and the high rate of bivalirudin, among others.

As regards the main topic, even though the absolute differences are quite small, it supports the hypothesis of an inverse correlation between volume and mortality. To sum up, if an operator lost 50 cases in one year, their mortality rate would increase a relative 4%. However, even though we know operator and center volume are important parameters, given the level of complexity our practice has reached, we should adopt a more holistic approach when assessing operators.

Courtesy of Dr. Agustín Vecchia.

Original Title: Outcomes of PCI in Relation to Procedural Characteristics and Operator Volumes in the United States.

Reference: 10.1016/j.jacc.2017.04.032.

We are interested in your opinion. Please, leave your comments, thoughts, questions, etc., below. They will be most welcome.