Outcomes/Effectiveness Research

Hospitals with low mortality rates for coronary bypass surgery also perform well in valve replacement

Heart valve replacement accounts for more than 20 percent of all cardiac procedures and more than 30 percent of all deaths after cardiac surgery. Individuals anticipating this surgery can find out about a hospital's performance of heart valve replacement surgery by looking up its coronary artery bypass graft (CABG) surgery mortality rate. That's because hospital mortality rates with CABG are closely correlated with mortality rates for valve replacement, according to a study supported in part by the Agency for Healthcare Research and Quality (HS10141).

The researchers studied operative mortality after CABG, aortic valve replacement (AVR), and mitral valve replacement (MVR) using the 1994 to 1999 national Medicare database. After excluding any hospitals that did not perform at least 50 CABG surgeries and 20 valve replacements per year, they examined the correlation between hospital mortality in CABG and hospital mortality in AVR and MVR at 684 hospitals.

When hospitals were grouped into deciles, the risk of death after AVR was about 6 percent when performed in hospitals with the lowest CABG mortality rates (lowest decile), but the risk doubled to 13 percent when AVR was performed in hospitals with the highest CABG mortality rates (highest decile). Similarly, the mortality rate for MVR was 10 percent in hospitals in the lowest decile of CABG mortality rates and nearly 21 percent in hospitals with the highest CABG mortality rates.

These correlations persisted regardless of whether valve replacement was performed with or without concomitant CABG or whether valve replacement was performed in a high- or low-volume hospital. These similar results may be the result of shared personnel and infrastructure (for example, same operating rooms and intensive care units) as well as processes of care shared between the two procedures. Improving these shared processes of care will likely help to make both CABG surgery and valve replacement surgery safer.

See "Do hospitals with low mortality rates in coronary artery bypass also perform well in valve replacement?" by Philip P. Goodney, M.D., Gerald T. O'Connor, Ph.D., Sc.D., David E. Wennberg, M.D., M.P.H., and John D. Birkmeyer, M.D., in the Annals of Thoracic Surgery 76, pp. 1131-1137, 2003.

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