What can be done to encourage doctors and other clinicians to heed new evidence when it shows the tests or procedures they are delivering are in fact not helping their patients—and may even harm them? This question has become increasingly relevant in the face of a growing number of studies casting doubt on the safety and efficacy of commonly used treatments and tests. Even when new evidence is clearly negative, clinicians often resist abandoning a service they have believed in, and developed expertise in, especially when that service provides a significant portion of their livelihoods.
Take the PSA, or Prostate Specific Antigen test, widely promoted for more than three decades to screen for prostate cancer. Most patients and physicians assumed that catching cancer early leads to a lower risk of death. But results from several large randomized controlled clinical trials, which compared men who received regular PSA screening versus usual care, showed little to no difference between the two groups in terms of their risk of dying of prostate cancer. The PSA test, it turns out, leads to the diagnosis of unthreatening tumors in 20 to 40 percent of cases.