There is tremendous unexplained variation in rates of surgical procedures from hospital catchment area to hospital catchment area, and region to region that cannot be explained by epidemiologic factors. For example, colleagues and I discovered in 1992 (see Spine, 1992) that the 15 fold difference in surgical procedures on the spine in Washington State was inexplicable by almost all population and diagnostic factors.
These sorts of studies were first called “small area analyses” by John Wennberg, MD, of Dartmouth Medical School–a specialist in internal medicine who then combined this with epidemiology and geography and who has a profound impact on understanding our heath care system–and those of other countries. His work has figured prominently in recently passed health reform, and figured prominently in policy alternatives in the Clinton administration. Quite simply, geographic variation is explained largely by different practice styles–and the greater the spatial variation, the less the consensus on the evidence base for proceeding in any given direction from a medical point of view. Put another way, the weaker the evidence base clinically, the greater the spatial variation in practice patterns. As Wennberg writes:
In Health Care, Geography is Destiny
Early in my career, I was hired as director of a federally sponsored program whose goal was to ensure that all Vermonters had access to recent advances in the treatment of heart disease, cancers, and stroke. As part of the program, my colleagues and I developed a data system that we thought would help us identify which Vermont communities were underserved, and thus in need of the program’s help. As the results came in, however, rather than evidence for underuse (i.e., patients not getting care they needed), we found extensive and seemingly inexplicable variation in the way health care was delivered from one Vermont community to another. In Stowe, for example, the rate of tonsillectomy was such that by age 15, about 60% of children were without tonsils, while in the bordering town of Waterbury, only 20% had undergone the surgery by that age. Among communities, the chances that a woman would have her uterus surgically removed varied by more than fourfold, and the rate of gallbladder surgery varied by more than threefold. Rates of hospitalizations for a host of different medical conditions also varied in ways that made little sense; on a per capita basis, patients were hospitalized in Randolph two times more often for digestive disease than in Middlebury and three times more often for respiratory disease.
Wennberg was the moving force behind Dartmouth’s “Atlas of Health Care” center, and subsequent centers for comparative clinical effectiveness. His work has spearheaded the whole movement of evidence-based medicine, the necessity of which became obvious from the mysterious spatial variations in care–mysteries originally uncovered by Wennberg nearly 40 years ago that in some counties, only 20% of teenagers were missing their tonsils, whereas in other counties, 70% had had tonsillectomies–with no seeming underlying rationality.
Wennberg has now published a thought provoking analysis of the implications of his work. Most significantly, it may be possible to eliminate billions of dollars from our health care bill without negative consequences for health status. These are funds that could then be allocated to increasing the access for disadvantaged groups.
So I highly recommend Tracking Medicine: A Researcher’s Quest to Understand Health Care, Oxford University Press, 2010, not only because it is a prime example of how geographic reasoning has had a profound impact on health care legislation, but as a glimpse into the intellectual history of an individual who has one of the deepest understandings of what lack of evidence-based medicine has done to our society.
For a local perspective on place-based and race-based health care provision and health outcomes, see the current American Prospect story, “Home Disadvantage,” about health disparities and people of color in Seattle’s South Park neighborhood.