The volume of cases performed at an institution each year has a direct effect on the outcome of surgical procedures, and should always be considered when looking at the benefits of a technique, according to a team of researchers at Henry Ford Hospital in Detroit.
Those conclusions will be presented May 5 at the annual meeting of the American Urological Association in San Diego.
The starting point of the study was the rapid increase in the use of surgical robots to assist in radical prostatectomy, in which the entire prostate gland and some surrounding tissue are removed to treat prostate cancer.
"This has happened in spite of a lack of randomized controlled studies to measure the superiority of robot-assisted radical prostatectomy, or RARP, over traditional open surgery to treat prostate cancers," says Jesse D. Sammon, D.O., a researcher at Henry Ford's Vattikuti Urology Institute and lead author of the study.
"There have been some studies recently that suggested an advantage for RARP in terms of complication rates from the time a patient is admitted for surgery, through the operation itself and until time of discharge from the hospital."
Dr. Sammon continues: "But these studies didn't take into account the relationship between surgical outcomes and the volume of surgery performed in a given institution. We set out to fill that void while comparing outcomes for RARP and open radical prostatectomy, or ORP."
Tapping data from the Nationwide Inpatient Sample – a set of databases maintained for researchers and policymakers to find and address trends in U.S. health care – the Henry Ford researchers identified 77,616 men who underwent radical prostatectomy in 2009. Of them, nearly 64 percent had RARP and about 36 percent had ORP.
The study then compared rates of blood transfusion, complications during and after surgery, prolonged length of hospital stay, elevated hospital charges and mortality within the test group.
"Overall, RARP patients experienced lower complication rates than those treated with ORP," Dr. Sammon says. "However, the picture changed when we factored in whether the procedures were done at very high-volume medical centers or low-volume institutions."
Low-volume centers averaged 26.2 cases of RARP and 5.2 of ORP, while the highest volume centers averaged nearly 579 RARP cases and 150 ORP cases per year.
When these caseloads were taken into account, the researchers found that among equivalent volumes, RARP results were generally favorable; ORP, however, at very high-volume centers, had lower complication rates after surgery and comparable rates of blood transfusions relative to RARP at low-volume centers.
"So, regardless of the approach – whether RARP or ORP – low-volume institutions experienced inferior outcomes when compared to the highest volume centers," Dr. Sammon says.