High volume equals high survival rate

Greater percentage of lung cancer survivors cited

Practice may not make perfect in medicine, but conventional wisdom and a growing body of literature support the notion that facilities that perform a large volume of certain procedures will achieve better outcomes. While previous studies had shown a correlation between hospital volume and positive outcomes for esophagectomy and pancreatectomy, as well as operations for breast cancer, colon cancer, and prostate cancer, there had been incomplete evidence of a similar association in the case of lung cancer surgery.

Now, a group of researchers from Sloan-Kettering Cancer Center in New York City have published their findings from a study that examined outcomes from resection for lung cancer. The study, which appeared in the July 19 issue of the New England Journal of Medicine, found the following:

• Five years after surgery, 44% of patients who underwent operations at the hospitals with the highest volume were alive, compared with 33% of those who underwent operations at hospitals with the lowest volume.

• Patients at the highest-volume hospitals also had lower rates of postoperative complications (20% vs. 44%) and lower 30-day mortality (3% vs. 6%) than those at the lowest-volume hospitals.

Patients selected from cancer registries

The patients studied were at least 65 and had received a diagnosis of stage I, II, or IIIA non-small cell lung cancer between 1985 and 1996, lived in one of the 10 study areas covered by the Surveillance, Epidemiology, and End Results (SEER) Cancer Registries, and underwent surgery at a hospital that participates in the Nationwide Inpatient Sample (2,118 patients and 76 hospitals).

The hospitals were characterized based on the number of lung cancer operations performed in 1997. In nearly half the hospitals (34 of 76), fewer than nine lung-cancer operations were performed in that year. By contrast, at 16 of the 76 hospitals, 20 to 66 procedures were performed in 1997, and at two hospitals, 67 to 100 were performed. Those facilities with the highest volume were generally teaching hospitals in urban areas.

The findings of the study underscore the importance of learning more about the connection between volume and outcomes, says lead author Peter B. Bach, MD, a pulmonary physician and epidemiologist at Sloan-Kettering. "Since approximately one in five patients diagnosed with lung cancer will have lung resection surgery, it is imperative to identify the possible reasons for the disparity and address it," he asserts.

So, is the answer as simple as it looks — that since larger volume hospitals do more of these procedures, they will have better outcomes? "No, I don’t think so," says Bach. "Clearly there is an association between increased volume and better outcomes, but these are just aggregate findings. Some lower-volume hospitals may be among the best in the country, and some larger-volume facilities may not be." There is the possibility, he concedes, that volume may actually reflect quality. "It’s extremely unlikely, but we can’t eliminate that possibility because some patients do go to specific hospitals because of the facility’s reputation."

In the article itself, the co-authors were careful to avoid any sweeping conclusions. "Survival might be improved by identifying the variations in preoperative and intraoperative care that are responsible for the differences we found,"1 they wrote. While noting that some observers suggest limiting the performance of resections for lung cancer to centers with better outcomes, the authors resisted that recommendation.

"We hesitate to advocate this . . . approach for three reasons. First, shifting surgical patients to a few institutions with high volumes of procedures may have unintended effects on the quality of care both at those institutions, which would face substantial increases in the volume of patients, and at the institutions with low volumes, where the care of the remaining patients might suffer," the authors said. "Second, increased volume and the teaching status of the hospital appear to be markers of improved outcome, but these characteristics do not, in isolation, identify individual high-quality hospitals. Finally, the association we observed between the volume of procedures and postoperative complications hints at the possibility that rectifiable variations in care may account for differences in outcome,"1 they concluded.

Reference

1. Bach PB, Cramer LD, Schrag D, et al. The influence of hospital volume on survival after resection for lung cancer. N Eng J Med 2001; 345:181-188.

Need more information?

For more information, contact: Peter B. Bach, MD, The Health Outcomes Research Group, Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., Box 221, New York, NY 10021. Telephone: (212) 639-7515.