A new study has confirmed what many doctors know intuitively: the more effort medical professionals have to expend selecting particular laboratory tests for their patients in an electronic test-ordering system, the less likely they are to recommend unnecessary procedures.

Researchers at the University of Missouri found that by altering the design of an electronic test-ordering system, they could significantly affect the overall volume (and cost) of diagnostic procedures. The finding could have implications downstream as many providers try to contain costs.

Under the first, “opt-in” model, no laboratory tests were preselected, and physicians had to check each diagnostic procedure they wanted to order. Most health facilities currently follow this method. In the second, ‘opt-out’ model, doctors had to deselect any tests they did not want performed. In the third model, only a few recommended tests were preselected by medical experts.

The study showed that physicians ordered the fewest number of tests when using the opt-in model, and ordered an average of three more tests per patient when using the opt-out model. On average, the opt-out method resulted in increased testing costs of $71 per patient. Doctors also ordered more tests when using the third, recommendation-based method than they did under the opt-in model.

“Ordering numerous lab tests can result in unnecessary testing and can cause physical discomfort and financial stress to patients,” said Victoria Shaffer, assistant professor in the University of Missouri School of Health Professions. “Essentially we found that including default selections—either with the opt-out method or the recommended method—increased the quantity of lab tests the clinicians ordered. Using a set of recommended defaults keeps costs down, but requires consensus about which tests to set as defaults.”

Shaffer’s coauthors included Adam Probst from Baylor Scott & White Health, and Raymond Chan from Children’s Mercy Hospitals and Clinics in Kansas City, Mo. Their study was published in Health Psychology