Surgical teamwork may explain volume-outcome differences

Complication rates may not be what differentiates mortality at high- vs. low-volume hospitals performing cardiovascular surgeries. Instead, it may come down to how surgical teams collaborate when complications arise.

In a study published in the February issue of JAMA Surgery, Andrew A. Gonzalez, MD, of the University of Illinois Hospital in Chicago, and colleagues explored mechanisms behind the volume-outcome effect. Increased hospital volume has been associated with improved outcomes in cardiovascular surgery, but they noted that studies also have shown the gap in complication rates between high- and low-volume hospitals was modest.

They proposed that the difference in failure to rescue, which they defined as a death of a patient after a major postoperative complication, may be a factor in postoperative mortality.

Gonzales et al used Medicare administrative data from 2005 and 2006 to identify 119,434 beneficiaries who underwent one of three surgeries: CABG, aortic valve replacement or abdominal aortic aneurysm. They focused on six medical and two surgical postoperative complications (pulmonary failure, pneumonia, MI [excluded for CABG], deep venous thrombosis or pulmonary embolism, acute renal failure, gastrointestinal bleeding, postoperative hemorrhage and surgical site infection).

Hospitals were divided into quintiles of procedure volume. They found that lowest-volume hospitals had significantly higher risk-adjusted rates for mortality for all three surgical procedures. Differences in the odds of postoperative complications were statistically significant but small for aortic valve replacement (odds ratio 1.12) and abdominal aortic aneurysm (odds ratio 1.18), and not statistically different for CABG.

High-volume hospitals achieved significantly lower failure-to-rescue rates. Differences in the odds between the highest and lowest volume hospitals ranged from a ratio of 1.16 for CABG to 1.38 for abdominal aortic aneurysm and 1.57 for aortic valve replacement.

“In our cohort, the FTR [failure-to-rescue] rates were 10.9 percent at high-volume hospitals and 13.3 percent at low-volume hospitals,” they wrote. “Were low-volume hospitals to have the same FTR rate as high volume hospitals, we estimate that 487 deaths would have been prevented during our two-year study period.”

They concluded that failure to rescue contributes to higher mortality at low-volume hospitals and is a key component in the volume-outcome relationship. Failure to rescue could encompass not only the surgical team’s skill at diagnosing and managing complications but also its ability to work cohesively in a crisis, they wrote.

“Although preventing complications is important, to make further gains toward decreasing mortality, clinical leaders should also seek to optimize the recognition and treatment of postoperative complications,” they recommended.