Analyzing and Sharing Data
Blue Cross Blue Shield of Michigan leadership and staff members have worked for the past year with John E. Wennberg, MD, MPH., of Dartmouth Medical School's Center for the Evaluative Clinical Sciences, to develop the Dartmouth Atlas of Health Care in Michigan. The Blues have met over the past several months to discuss the project with the Michigan State Medical Society, Michigan Osteopathic Association, Michigan Health and Hospital Association, the United Auto Workers and large Blues customer groups such as the auto companies.

The "atlas" is the most extensive study of its kind of medical care in Michigan. Dr. Wennberg and his associates used Blues' claims data and information from other sources to analyze the use and supply of health care services. The data was provided in such a way as to protect the confidentiality of individual Blues members but to allow for analysis based on geographical areas.

The Blues commissioned the study as a way to open statewide, interdisciplinary discussion and action about important health issues we face together. The goal is to work in partnership with the physician and health provider community and community groups to discuss the atlas findings and ways they can be used to enhance the quality of health care in Michigan. The atlas is also a component of the Blues' long-term corporate strategy to analyze and share data with hospitals, communities and physicians. The atlas should be viewed as a tool or starting point for community dialogue. It does not give answers for the variations but it will generate questions.

Inside the Atlas
The Michigan atlas publication includes color-coded maps showing the regional rates of certain surgical procedures and pharmaceutical services, the supply of physicians and hospital beds, and other health care data. The atlas illustrates among other things how health service use varies across the state.

Instead of cities and counties, the atlas is based on geographical units called Hospital Service Areas (HSAs)-local markets for community-based hospital care. Each HSA is a combination of zip codes. The study examined services rendered to individuals who live in those areas, regardless of where they actually received care. Larger geographic units called Health Referral Regions (HRRs) are used to analyze tertiary services.

Dr. Wennberg and the American Hospital Association worked collaboratively on a series of Dartmouth Atlases, including the original published in 1996. Both viewed the atlas as means to engender debate among key stakeholders about variation in health care. The Michigan atlas will use Blues claims data instead of the Medicare data that was used in national atlases. The national studies were primarily linked to inpatient hospital data. The Blues' database allows for the study of a wider range of services and a broader population than previous atlas publications.

Notably, the Michigan publication will be the first of its kind to examine the use of pharmaceutical services. It will address prescribing patterns for several drug categories: antibiotics, attention deficit disorder drugs, anti-depression and anti-anxiety drugs, proton pump inhibitors, antihistamines, ACE inhibitors, beta blockers and lipid lowering agents.

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NOTICE TO ATLAS READERS
While not giving answers, the atlas raises questions about health care service use that merit careful consideration. "High" rates of use are not necessarily bad and "low" volumes good (or vice versa). Our goal is to move toward rates that are consistent with high quality health care, which need to be determined with local clinical, community and patient discussion and dialogue.

The atlas is not a physician or hospital report card. When reviewing data, note that the Hospital Service Areas in the atlas were defined by the atlas author. They may differ significantly from what a hospital considers its market area.