Three-year data on surgical patients in Pennsylvania support using surgeon and hospital volume as part of the credentialing process for bariatric surgery centers of excellence, according to a study of 14,716 patients who underwent bariatric surgery in Pennsylvania hospitals from 2000 to 2003.
Dr. Ann M. Rogers and her associates at Pennsylvania State University, Hershey, analyzed the relationship between surgeon and hospital volume on length of stay, in-hospital mortality, and 30-day mortality after adjusting for age, gender, ethnicity, payer, and score based on the severity of the patients' illness.
They found that bariatric surgery “performed by high-volume surgeons in hospitals where more than 100 cases were performed a year was associated with decreased mortality and length of stay, compared to those patients whose surgeons operated on fewer than 100 cases per year at hospitals with fewer than 100 cases per year.”
Individual surgeons and hospitals were stratified into one of three categories: high volume (more than 100 cases per year), medium volume (50–100 cases per year), or low volume (fewer than 50 cases per year).
During the time period of the study, which was presented at the Academic Surgical Congress, the mean surgical volume per hospital increased from 20 to 120 cases per year, and in-hospital mortality decreased from 0.8% to 0.2%. Overall, 30-day mortality was 1.15%, and in-hospital mortality was 0.37%.
After controlling for other factors, the investigators found that 30-day mortality was 3.7 times higher among those treated by low-volume surgeons and 2.8 times higher among those treated by medium-volume surgeons, when compared with those treated by high-volume surgeons, which were significant differences.
In addition, 30-day mortality was 2.3 times greater for patients treated in low-volume hospitals and 1.6 times greater in medium-volume hospitals than in high-volume hospitals, which were significant differences.
Length of stay was significantly shorter in high-volume hospitals than in low- or medium-volume hospitals. “Our data showed progressively increasing length of stay from high- to medium- to low-volume hospitals and surgeons,” Dr. Rogers said in an interview.
Medium-volume hospitals and surgeons were associated with about half a day longer length of stay, while low-volume hospitals and surgeons were associated with about an additional day and a half in the hospital, compared with those in the high-volume hospital and surgeon group, said Dr. Rogers, director of the Penn State surgical weight loss program.
Male gender and admission severity, as well as hospital and surgeon volume, were significantly associated with increased in-hospital and 30-day mortality. Men were at a 3.6 times greater risk for in-hospital and 30-day mortality, compared with women, which was significant, she said.
Dr. Rogers of the department of surgery at the Penn State Milton S. Hershey Medical Center, Hershey, said there is a fairly large body of literature looking at the impact of surgeon and hospital volume on the outcomes of bariatric surgery, but that the Penn State group, spearheaded by Dr. Robert N. Cooney, is only the third to evaluate 30-day mortality, rather than in-hospital mortality alone.
Since 2006, when the Centers for Medicare and Medicaid Services decided to cover bariatric surgery performed at centers listed with the American Society for Bariatric Surgery/Surgical Review Corporation Center of Excellence or as an American College of Surgeons Level One Center of Excellence, hospitals have been under increased pressure to obtain bariatric surgery credentials.
As a result, many third-party payers either require that patients be treated only in credentialed centers or have created their own criteria for a center of excellence, Dr. Rogers noted. Surgeon and hospital volume are both considered in the credentialing process, and “we believe our results support the use of such criteria in the credentialing process” of both hospitals and surgeons, she said.
Studies of other surgical procedures have demonstrated higher morbidity and mortality associated with low-volume surgeons and hospitals, Dr. Myriam Curet said in an interview. The Penn State study confirms the finding that the relationship between volume and patient outcomes is also true for bariatric surgery, said Dr. Curet, a bariatric surgeon and professor of surgery at Stanford (Calif.) University.
This type of evidence was the impetus behind using the volume criteria for centers of excellence certification, “and this study confirms that this was the correct decision,” she added. “If we're all aiming to improve patient outcomes, then having these kinds of volume criteria to designate centers of excellence is clearly important.”