Does Practice Really Make Perfect?

Surgery is risky. Worries include surgical errors, perioperative complications, difficult recovery, and poor long-term outcomes. Given the high stakes of surgical treatment, where should patients go when they need surgery? Common sense and a growing literature suggest that they should seek surgeons and hospitals that frequently perform the needed procedure. After all, practice makes perfect, doesn't it? Two studies reported in this issue suggest that the answer to this question is considerably more complicated than it appears (1, 2).

In raising questions about volume–outcome relationships, these studies swim against a strong current. Corporate America embraces the notion that practice makes perfect. Organizations that evaluate health care offer profiles that feature volume prominently (3-5). The Leapfrog Group, a coalition of more than 140 companies convened to improve the quality of health care for their employees, believes that the evidence links high procedure volumes to favorable outcomes and recommends specific volume thresholds for a variety of procedures (6). Many who study health care delivery also believe that high volume means superior outcomes. Researchers analyzing the potential benefits of the Leapfrog Group's volume standards for 5 high-risk surgical procedures estimate that the requirements would save 2581 lives annually (7). A reviewer of 20 years of volume–outcome studies concluded that high volume is associated with better outcomes across a variety of conditions (8).

Several potential explanations lie behind past conclusions that surgical patients fare best with high-volume providers. The first is that practice really does make perfect. To test this hypothesis, we ask whether patients who underwent surgery at low-volume hospitals or by low-volume surgeons would have done better had they gone to high-volume providers. A definitive answer to this question would require a randomized trial, but only observational data exist. Observational studies of volume–outcome relationships examine aggregated data …