As a way to cut overall imaging utilization and spending, increased patient cost-sharing via high-deductible health insurance seems to work. But the approach may not do much to help patients tell medically recommended exams from frequently wasteful ones. (MRI for low-back pain, we’re looking at you.)

Sarah Zheng, MA, of Boston University’s Questrom School of Business, and colleagues arrived at this by looking at commercial insurance claims data on more than 21 million individuals.

Comparing utilization of, and payments for, enrollees in high-deductible health plans (HDHPs) with the same metrics on enrollees in non-HDHP plans, they found that HDHP enrollment was associated with a 7.5 percent decrease in the number of imaging studies done and a 10.2 percent decrease in dollars laid out for imaging studies.

Interestingly, HDHP enrollees were less likely than their non-HDHP counterparts to utilize imaging at all—but, once an HDHP enrollee had at least one imaging study, he or she was further imaged at close to the same rate as those in the non-HDHP cohort.

The researchers recorded the greatest dips in utilization occurring within the lowest risk-score tercile (i.e., the least sick patient subgroup).

Their study is running in the February edition of Medical Care.

While Zheng and colleagues were unable to determine whether the reduced imaging use associated with HDHP coverage was high- or low-value—a key consideration in tracking patient outcomes—they note that their results echo previous research.

“[H]igh-deductible health plans may be a blunt instrument reducing all diagnostic imaging, rather than helping physicians and patients choose high-value imaging,” they point out in a press release from the journal’s publisher, Wolters Kluwer.

Increased cost-sharing, the authors conclude, “may not encourage patients to differentiate between high-value and low-value diagnostic imaging services; better patient awareness and education may be a crucial part of any reductions in diagnostic imaging utilization.”