SUMMARY: It’s hard to find good quality measures in health care. One good proxy measure for quality is frequency: The doc who does more knee replacements tends to be good at doing knee replacements. It’s not always strictly true, but often is.
We are often asked about quality measures — who’s the better doc, the better hospital? The industry is challenged in this regard: do we like better outcomes, better bedside manner, fewer days in the hospital, lower waiting times? Or do we like longer waiting times for a worse bedside manner if the doctor has a great reputation?
One metric that seems pretty good is frequency — up to a point. If a provider is doing more procedures in a year than is humanly possible or reasonable, then of course one should question. But generally frequency is a good measure.
“Historically, the volume–outcome relationship has been explained by ‘practice makes perfect’ or patient selection (i.e., ‘busy doctors see healthier patients’). The authors propose a conceptual model that identifies a series of factors that might underlie the relationship between volume and quality of care,” says a well-known paper on the topic, Interpreting the Volume-Outcome Relationship in the Context of Health Care Quality: Workshop Summary ( 2000 ) / How is Volume Related to Quality in Health Care?, which came out of a workshop at the Institute of Medicine in 2000.
“The authors conclude that for a wide variety of surgical procedures and medical conditions, higher volume (whether assessed by hospital or by physician) is associated with better health outcomes. The uniformity with which the published research documents or confirms the existence of this association is compelling (although the review authors caution that a publication bias against negative findings cannot be ruled out)…
“Statistically significant associations between higher volume and better outcomes were found in 79 percent of the studies of hospital volume and 77 percent of the studies of physician volume.
“None of the studies reviewed showed a negative effect of volume….
“Volume is, however, an imprecise indicator of quality. Some low-volume providers have excellent outcomes, and conversely, some high-volume providers have poor outcomes. Volume per se does not lead to good outcomes in health care; it is instead a proxy measure for other factors that affect care. With few exceptions, however, the literature does not shed light on the structures or processes of care that underlie the apparent relationship.
“Many workshop participants noted that volume may be the best available proxy indicator of quality for certain conditions, but efforts should be made to accompany volume information with other quality indicators and with explanatory information. Furthermore, several participants suggested that when research confirms a volume–outcome link, this information should be disclosed to the public to support health care decision-making. In making such disclosure, however, the limitations of the data and how to interpret the information must be made clear to the intended audience. Public release of data on volume may motivate providers to report process and outcome data, thereby laying the ground for the next generation of health care quality measures.”
“The workshop was structured around presentations of two background papers: a cross-disciplinary, systematic review of the published research literature conducted by Drs. Ethan Halm, Clara Lee, and Mark Chassin of the Mount Sinai School of Medicine and a synthesis of the literature relevant to policy issues by Dr. Adams Dudley and colleagues from the University of California, San Francisco.”
