A Swedish initiative to spur appropriate imaging use in prostate cancer by providing utilization data and guidelines to clinicians caused the rate of inappropriate scans for low-risk patients to nose-dive, according to a study published online July 23 in the Journal of the National Cancer Institute.

However, appropriate imaging in high-risk patients also saw a slight decline over the study period, which provides a lesson for those crafting appropriate imaging initiatives in the U.S., wrote Danil V. Makarov, MD, of NYU Langone Medical Center in New York City, and colleagues.

“Although appropriate imaging suffered to a small extent, these national-level results are truly remarkable because many previous guidelines and policy efforts have failed to reduce inappropriate prostate cancer imaging in the United States,” wrote the authors.

Since 2000, the National Prostate Cancer Register (NPCR) of Sweden has tried to discourage inappropriate prostate cancer imaging by giving imaging guidelines to urologists along with utilization data. The guidelines indicate that imaging evaluation for low-risk disease is mostly unnecessary.

To gain some insight into how this effort influenced utilization, Makarov and colleagues conducted a retrospective cohort study of nearly 100,000 men diagnosed with prostate cancer from 1998 to 2009.

The analysis revealed that overall imaging use decreased over time for all regions, led by a drop in low-risk patients, reported the authors. Rates of imaging for low-risk prostate cancer patients plummeted from 45 percent to 3 percent over the study period.

In high-risk patients, who should be imaged, according to the guidelines, imaging rates also fell from 63 percent to 47 percent. Makarov and colleagues said this was a smaller, but statistically significant, drop.

The researchers noted that imaging is still indicated for low-risk patients who are experiencing bone pain, and with as many as 28 percent of men older than 50 reporting back pain, the optimal rate of imaging should not be zero. “This 3 percent rate undoubtedly encompasses some patients presenting with prostate cancer and unrelated back pain, in whom a bone scan is indicated but whose rates of metastatic prostate cancer are vanishingly small.”

Because the study was retrospective, it could not definitively determine causality, and Makarov and colleagues noted that a number of unmeasured confounding variables could have altered imaging rates.

Previous studies have also found that reductions in inappropriate testing tend to be accompanied by drops in appropriate imaging as well, even if these latter reductions are smaller. The researchers suggested that efforts to curb inappropriate prostate cancer imaging be paired with efforts to encourage appropriate use.

“The Swedish experience could inform future US health policy efforts, such as the Choosing Wisely campaign, in several ways,” wrote the authors. “Policymakers should be encouraged that they have selected a solvable problem.”