CHICAGO (AP) — A new study suggests that in a single year, up to 42 percent of Medicare patients got at least one medical procedure they didn’t need — overtreatment that cost as much as $8 billion.

The treatments included cancer screenings beyond the age most experts recommend. They also include invasive heart and kidney procedures that research has shown are no better than medicine, and potentially more risky.

The researchers analyzed Medicare claims data for 1.3 million patients in 2009. They devised a list of 26 “low-value” procedures they determined reflect likely overuse. The list was compiled from research evidence and recommendations from several medical groups.

The results were published online Monday in JAMA Internal Medicine.

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