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It has long been known that there is variation in the use of elective procedures based on location. But much of the variation cannot be explained by differences in illness prevalence. This research shows that one of the best predictors of undergoing many elective procedures and tests is the community where a patient lives and the prevailing medical practices of clinicians in that area.

Some dramatic examples from the data are:

• In the Deer Park area, the rate of knee replacement increased by 62% from the 2005–2008 period through the 2009–2012 period. Deer Park area residents are twice as likely to have knee replacement surgery compared to those in the Hawthorne area, where this kind of surgery was below the state average rate during 2009–2012.
• During the 2005–2008 period, Clearlake had the highest rate of angiography in the state. By the 2009–2012 period, the rate there had dropped by 47%, but people in this area are still four times more likely to undergo an angiography than those in Mountain View, where the angiography rate was below the state average during 2009–2012.
• Women in Gardena, where the rate of elective induction increased by 95%, are six times more likely to have an electively induced birth as women in Napa, whose induction rate was significantly below the state average.
• Women in Paramount, where the rate of Cesarean section increased 25% between 2005–2008 and 2009–2012, are more than twice as likely to deliver by c-section as women in Grass Valley, where the rate dropped by 24% during that same time.

In the video below, UC San Francisco cardiologist Rita Redberg, MD, talks about the negative effects of variation on patients’ health and medical costs and what can be done to change it.

The research includes Medicare patients and younger populations enrolled in commercial plans, Medicaid patients, and the uninsured. For complete details on data sources, reporting periods, study methodology, risk adjustment, hospital service area versus hospital referral region, how “elective” is defined, and other factors considered in medical variation, see the report, All Over the Map: Elective Procedure Rates in California Vary Widely, under Document Downloads. Discussions of the procedures studied are available in the Close Up reports.

A Clearer View: Humboldt Steps Out of the Fog of Medical Variation

Following a 2011 CHCF study of geographic medical variation in California, leaders in Humboldt County came together to examine the causes of variation in their region. The full story is available in PDF below.