Are Randomized Controlled Trials Relevant to Clinical Practice

Steven D Hollon, PhD1; Bruce E Wampold, PhD, ABPP2 Can J Psychiatry. 2009;54(9):637-643. Randomized Controlled Trials Are Relevant to Clinical Practice I think that randomized controlled trials (RCTs) are highly relevant to clinical practice. If I had a serious medical illness, I would want to know that what I was about to receive actually worked and how it fared relative to other treatment options. Saying that something works means that it has a causal effect (relative to its absence), and saying that it works better than other options means that its impact is even larger than those other options. The most powerful method yet devised to determine whether something has a causal effect (or how it compares with other options) is to test it in an RCT. I think that people with psychological disorders deserve the same level of certainty as people with medical disorders; I want to know whether what I do works. I do not defend RCTs because I conduct them, I conduct RCTs because I can defend them. All causal inference starts with observation. If I want to know if a treatment works, I want to know what happens to people who get treated. If I had a serious medical illness, the first thing I would do is talk to other people who had the disorder and find out what they did and how it went. The problem with relying on such anecdotal observations is that I could never know whether what happened was a consequence of treatment. I would be glad if all the outcomes were benign, but that would not tell me that treatment was necessary to produce those happy outcomes. When my son was growing up he played soccer with teammates who were spanked by their parents when they misbehaved. When those parents observed that we did not spank our son, they were curious as to how we expected him to learn right from wrong. Their parents had spanked them when they were young and they had turned out well. Therefore, they believed it was their obligation as caring and responsible parents to spank their children if they wanted them to turn out well. The fact that something happens does not mean that is was caused by what you did. I may decide to talk to people who had been treated and others who had not (if any were still living) and see how each turned out. This is a quasi-experiment in which people are exposed to different treatments and their subsequent outcomes are observed. The problem with this strategy is that it confounds individual differences with differential treatment. Considered medical opinion for the last several decades has been that women going through menopause benefited from hormone replacement therapy. Women who were treated with estrogen did appear to do better than women who were not. The problem with this inference was that women were free to choose whether they received estrogen or not and those who choose estrogen typically took better care of themselves and had better access to health care. When the field finally got around to doing an RCT on adding estrogen, the study was stopped before completion because replacement therapy increased the risk for cancer and heart disease.1 It is not that the doctors providing hormone replacement therapy did not care about their patients or that the women treated with it did not care about their health. We simply did not have the right kind of data to draw an accurate causal inference, and a generation of women suffered as a consequence. Randomization is designed to control for individual differences. If people sort themselves into conditions for reasons related to the differences between them then any subsequent outcomes observed could be as much a consequence of preexistent individual differences as a consequence of treatment. Good intentions are not enough to do right by patients; hard data are needed that speak to the causal potency of a treatment. RCTs remain the single best (but not the only) way to collect such data. RCTs control for spontaneous remission and other factors related to the passage of time, and they control for individual differences that can affect subsequent course. …