This interactive map presents elective surgery and other procedure rates across California relative to the state averages and shows widely varying rates in spite of data adjustments for disease prevalence and other factors. The research findings are presented in multiple formats below the map.

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Some examples from the data (click each item to see it in the map above):

• Marysville region residents have coronary artery bypass graft surgery at 264% of the state average rate.
• Red Bluff region residents undergo knee replacements at 200% of the state average rate.
• Women who live in the Berkeley area deliver vaginally after having had a cesarean section at 301% of the state average rate.
• Ridgecrest residents (in the San Bernardino area) have gallbladder surgery at 177% of the state average rate.

While some geographic variation in surgical rates is expected due to differences in the prevalence of disease, note the authors, much of the variation seen in California cannot be explained by illness rates. The authors noted that for elective procedures, a patient's own values and willingness to accept uncertainty in outcomes should be considered alongside the clinician's recommendations.

The data include Medicare patients as well as younger populations enrolled in commercial plans, Medicaid, or who are uninsured. The consistency of results across all payers makes this a significant contribution to the literature documenting regional variation.

Available below are these Document Downloads:

• A summary discussing key factors in medical variation research and the important role that patient input can play in treatment decisions.
• Seven reports ("Close-Ups") providing detailed data on the 13 procedures examined here.
• A spreadsheet showing related data on prevalence of heart attacks, a proxy for severe cardiac disease, in California.