Austin Frakt, health economics blogger extraordinaire at The Incidental Economist, has a post up commenting on Kenny Lin's post about shared decision-making and PSA testing. The following is an edited comment I posted on that article:
I have to disagree with Kenny on this one, despite having written an article
in the NYTimes Magazine that strongly supported Kenny’s work at the US Preventive Services Task Force, which found that PSA testing does not offer a mortality benefit.
Shared decision making is not about getting the patient to do what the doctor wants him to do, which judging from Kenny’s blog he thinks it is (and his opinion about the PSA test is, understandably, “Just don’t do it!”).
Frankly, as a patient, I find myself bristling when doctors (even those who are caring and well-informed) insist that they know best about what I want to do with my body. The point of shared decision making is to help patients: a) understand that ELECTIVE decisions mean the patient has a choice; b) understand the tradeoffs involved in each of the choices; and c) come to a decision that is in keeping with their values and preferences. It doesn't remove the doctor from the decision-making process, but it's not just telling patients what to do and using research to cover it up.
What I think Kenny is saying (apologies if I'm misinterpreting!) is that PSA testing shouldn't be considered an elective test—it shouldn't be presented as an option at all. I don’t know what the right answer is there, but there is a reasonable case to be made that some men might still want it, even after understanding as much as Kenny does about how lousy the test is. And it is a lousy test — as one researcher puts it, PSA predicts whether you have prostate cancer about as well as your eye color predicts the same. But while the randomized controlled trials did not find an all-cause mortality benefit from PSA testing, there’s evidence to suggest that it might possibly reduce your chances of dying from prostate cancer, though not by much. So for a man who would rather die of ANYTHING but prostate cancer (and would even prefer to die from the treatment for it) the test might be a good choice. He values avoiding a prostate cancer death, and while early diagnosis is no guarantee that he will, he might.
So while I think getting a PSA test is a really bad idea, and I don’t think I would get one myself if I were a man, and I’m glad my husband decided to forgo the test after viewing a patient decision aid, maybe it should still be considered an elective decision.
More broadly, what do the data say about shared decision making and its effect on patient decisions? A Cochrane Collaboration systematic review of more than 80 prospective RCTs comparing patients who had access to a patient decision aid (for lots of different elective decisions) and those who got usual care (the doctor tells them about their choices) found that patients who have access to an aid are better informed about the risks and benefits involved in their choices; are more realistic about those tradeoffs; and are on average 20% less likely to choose more invasive options. (That last finding is why policy makers get all excited about shared decision making.)
When you look specifically at studies of shared decision making for PSA testing, it’s not so clear that men are less likely to choose the test. There are a couple of possible reasons. I can’t pretend to have looked at all of the studies, but from a few that I’ve seen, it’s not surprising that men opt for the test because the so-called patient decision aid that was used urged them to get tested. The other reason I think its hard to dissuade men from getting tested is we have been beating the screening drum in the US for a long time. It is an article of faith that catching cancer early is universally good. It is going to take a long time to unlearn that myth.
Conclusion: discarding all of shared decision making on the basis of PSA testing is a bad idea.