A Michigan Look at Variation in Medical Care: Where you live often determines what you get

October 4, 2010

This week our Center is releasing a report on geographic variation in health care use in Michigan. Geographic variation in the use of health care services has been well described in the literature for more than 20 years now. Jack Wennberg pioneered this kind of systematic analysis at Dartmouth and has been reporting this data on an ongoing basis looking at the Medicare population. In 1997, Jack partnered with Blue Cross and Blue Shield of Michigan to do the same kind of analysis looking at a commercial, under 65 year old population. The report in Michigan got a lot of attention when it was released in 2000 – and sparked some interesting community dialogs including one in Grosse Pointe, Michigan about why their rates of use for ADHD drugs was so high (highest in the state).

Earlier this year we decided that it was time to do a 10 year snapshot and see what has changed – and what hasn’t – since the report was first released. And, we did, indeed find some very interesting things. On the good news side of the equation, we found that overall use rates for diagnostic and interventional cardiac procedures went down. This compares favorably to trends elsewhere in the country: most recent national data shows an increase in use rates for the three services combined.

The data on cardiac care shows us what’s possible: we truly believe that there is a connection to the fact that there is now less surgical intervention for cardiac care in Michigan because of an effort that was started in 1996 between Blue Cross and Blue Shield of Michigan and the University of Michigan in partnership with all hospitals performing cardiac procedures in the state. In that partnership, called a Collaborative Quality Initiative (CQI), use trend data and best practices information is shared between clinicians performing these procedures. The dialogue in that process focuses on quality improvement. The 10 year data we see in the CHRT geographic variation report gives us some indicators about the power of this approach and its ability to affect practice patterns across the state.

Some concerning findings in the report include the very significant increase in the percentage of babies in the state now born by Cesarean section (up from 22.9 percent in 1997 to 34 percent of all Blue Cross births in 2008) and the high rates of use in some areas of the state on virtually every procedure studied (Saginaw, the “Thumb”).

The issue of Cesarean sections is national – indeed, global – and of significant public health concern. Healthy People 2010 set a goal of no more than 12 percent of births by C-section in the US by 2010. Our data (among other national studies) show that not only was that goal not achieved, but, that the trends are all in the wrong direction. This finding calls out for a CQI or other similar effort to better understand why and what could be done about it.

The reasons behind second issue of concern, the high rates of use in some regions compared to others on almost every procedure, are less clear. To the best of our ability, we adjusted the data for patient demographics: age, gender and severity of illness. So, it should not be patient characteristics that results in this variation. We will do more studies on some potential issues that might be contributing to those use differences and now that this data is available, we hope that practitioners in those areas will also consider what might be driving these differences.

Finally, there are gems in the data that should trigger some deeper looks at what is happening in the community. For example, 10 years ago, St Joseph, Michigan had the lowest rate of angioplasty in the state; today, they have one of the highest. It isn’t because their rates actually went up. Rather, the whole rest of the state came down while rates in St Joe’s didn’t change. Why not? What is happening in that community that resulted in a different trajectory than the rest of the state? That’s the kind of question that we hope this study – and others to follow – will spark.