Higher volume may not guarantee higher quality angioplasty and stenting

"Practice makes perfect" seems logical, but how much practice remains uncertain, and current health care quality guidelines may be set too high. It may be time to reexamine the standard recommending hospitals perform at least 400 angioplasty and stent procedures per year, according to a new study in the May 19, 2004 issue of the Journal of the American College of Cardiology.

"The 400 level might be too high, at least from an evidence point of view," said Harlan M. Krumholz, MD, FACC from the Yale University School of Medicine. "We don't have evidence that you always need to go that high to get the same outcomes. The minimum volume standard is probably a moving target with evolving technology and cumulative operator experience. As a result we might be better served with something other than the volume standard, except for the very lower end of the spectrum. Instead, we should develop more of an outcome-based assessment."

Both the Leapfrog Group (a collection of large health care purchasers) and the American College of Cardiology/American Heart Association guidelines recommend that hospitals perform at least 400 percutaneous coronary interventions (PCI) a year. The procedures include angioplasty and stent placement to reopen coronary arteries.

In order to see whether that standard actually predicted better patient survival, Dr. Krumholz, along with Andrew J. Epstein, MPP and others at Yale and the University of Pennsylvania, analyzed federal administrative billing records on 362,748 patients who underwent PCI between 1998 and 2000. They compared death rates while patients were still in the hospital to the procedure volume for the hospital.

After adjusting the data to account for differences in disease severity, age, and other patient characteristics, the researchers found that although death rates were higher in low-volume hospitals (less than 200 procedures per year), there was not a statistically significant difference between the death rates in medium-volume hospitals (200 to 399 procedures per year) and those in high or very-high volume hospitals (400 procedures or more per year). The study did not evaluate the success of the procedure or the occurrence of non-fatal complications.

Dr. Krumholz said the results of this study indicate that while patients may have reason to question the performance of low-volume hospitals that average less than one procedure a day, there may be legitimate reasons for choosing a hospital that doesn't quite meet the standard of 400 procedures per year.

"We're saying that if a hospital is in the medium-volume category, we don't have any evidence that you are losing anything by going there. And people may have a lot of reasons for going there; they may want to stick with their doctor, they want to stay closer to home and so on," Dr. Krumholz said.

Dr. Krumholz also noted that even though the average death rates in low-volume hospitals were higher, a number of the hospitals included in the low-volume group had better outcomes than hospitals with higher volumes. Given the results of this study, he questioned the common use of procedure volume as a stand-in for hospital quality. He said it's time to start judging hospitals by how well patients actually do.

"If you are doing these procedures, you have the information that says how well you're doing. We need to know the outcomes. The only reason we are using volume is as a surrogate for those outcomes. And we'd be better off knowing the real answer, which is how the hospital is doing," Dr. Krumholz said.

In an editorial in the journal, Alan C. Yeung, MD, FACC at the Stanford University Medical Center in Palo Alto, Calif., wrote that any reevaluation of the volume standards should proceed cautiously. He noted that the study by Krumholz et al. was based on billing records and so did not include potentially important clinical details of patients. In addition, he said the volume of individual practitioners should be examined.

"These days with better techniques and better technology, the cut-off of 400 cases per hospital for mortality and other outcomes may have shifted a bit lower. But the difficulty is that there are many other factors that potentially play a role," Dr. Yeung said.

The American College of Cardiology, a 29,000-member nonprofit professional medical society and teaching institution, is dedicated to fostering optimal cardiovascular care and disease prevention through professional education, promotion of research, leadership in the development of standards and guidelines, and the formulation of health care policy. http://www.acc.org

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