More heart transplants done, better outcomes

Hospitals that do fewer than 14 heart transplants a year see significantly more patients die within 30 days than do higher-volume transplant centers, according to a study of United Network for Organ Sharing data.

Researchers argued that physicians and policymakers should steer patients toward high-volume transplant centers to get better outcomes.

But other experts said transplant volume is not the only factor that should be considered when aiming for quality.

"This is not a new concept," said study co-investigator John V. Conte, MD, director of heart and lung transplantation at Johns Hopkins Hospital in Baltimore, which handles 20 to 30 heart transplants annually. "The evidence shows that the more you do of any complex procedure, the better that people are going to be at it."

Previous studies documented a relationship between surgical volume and outcomes.

Dr. Conte and his colleagues at Johns Hopkins' cardiac surgery division evaluated 30-day mortality rates for more than 14,000 heart recipients at 143 transplant centers from 1999 to 2006. They presented their findings at the Society of Thoracic Surgeons annual meeting in late January.

Centers that did more than 10 heart transplants a year averaged a 5.6% one-month mortality rate. That rate was 52% lower than centers that did fewer than 10, 64% lower than those that handled less than five cases and nearly two times lower than centers that averaged two cases or less.

Meanwhile, patients who received new hearts at centers that conducted fewer than 10 heart transplants had a 30-day mortality rate 80% higher than the national average. Those who got hearts at one of the eight centers that does more than 40 heart transplants a year were half as likely to die within 30 days, compared with the national average.

The mortality rates for the majority of patients flattened at centers that performed 14 or more heart transplants, researchers found.

Qualifying for reimbursement

The findings, which have been submitted to The Annals of Thoracic Surgery for publication, come on the heels of a March 2007 Centers for Medicare & Medicaid Services rule. The new regulation set an annual volume threshold of 10 heart transplants that hospitals must meet to qualify for federal reimbursement.

In its rule, Medicare said higher-volume centers are better for patients but "there is no evidence that indicates what the minimum threshold should be." Volume requirements for transplant centers were picked because they are close to the agency's national coverage decision thresholds and are designed to make sure transplant centers "stay active."

Jeffrey D. Hosenpud, MD, looked at UNOS data from 1987-1991 for a study in the June 15, 1994, JAMA that found a less pronounced volume-outcome correlation. Centers that performed fewer than nine heart transplants had a 40% higher 30-day mortality rate than those that did more than nine. Yet Dr. Hosenpud was not quite ready to agree with the 14-transplant threshold identified by Hopkins researchers.

"There is clearly a breakpoint in outcomes," said Dr. Hosenpud, a cardiologist at the Mayo Clinic in Jacksonville, Fla. "And there's no doubt there's a curve that breaks somewhere in the 10-to-15 range. From a policy standpoint, that's probably as good as you can get as far as understanding the impact of volume on outcomes."

Maryl R. Johnson, MD, is medical director of heart failure and cardiac transplantation at the University of Wisconsin School of Medicine and Public Health in Madison, which does about 20 heart transplants a year. She said doctors should consider a center's volume when referring patients but that should not be the only factor.

"Volume is important," said Dr. Johnson, secretary-treasurer of the American Society of Transplantation. But it could be outweighed "if you're looking at a center with low volume that still has pretty good outcomes, especially if it's in an area that doesn't have many other good options."