Why Waitlist Control Groups in Psychotherapy Research Studies Suck

It’s long been recognized that the gold standard in medical drug research is a randomized, placebo-controlled study. While not without its faults, this type of research ensures that the drug being tested is more effective (and just as safe) as a pill that contains no active ingredients. That way, the data can show that secondary effects — such as the act of taking a pill once a day or seeing a doctor for refills or collecting study data — aren’t the main cause of any benefits the research may find.

In psychotherapy research, there is no pill. So a long time ago, some researchers developed what they believed to be a similar control group as those receiving a placebo — the waitlist control group. The wait-list control group is simply a group of subjects randomized to be placed on a fake “waitlist” — waiting for the active treatment intervention.

But there are more than a few problems with this type of control group in research. In a word, waitlist control groups suck.

Here’s why.

Waitlist control groups were conceived by researchers as a cost-effective and ethical alternative control group when primarily studying psychotherapy interventions. That’s because providing a sham psychotherapy treatment is unethical — psychologists can’t knowingly provide you a treatment that they know doesn’t work.

Gallin & Ognibene (2012) define a wait-list control group as a group of participants who “are denied the experimental treatment, but are aware that they are not receiving treatment. […] Wait-list groups really are not untreated because they are contacted, consented, randomized, diagnosed, and measured.”

The problem comes with psychotherapy research that uses a wait-list control group to demonstrate that the treatment is more effective than simply time alone. Most researchers recognize that for many mental disorders — especially when the disorder is mild — many people will get better with time alone, on their own, with no active treatment.

So the goal of such wait-list control-based research is to show the psychotherapy treatment is more effective than doing nothing. But that’s such a low hurdle to clear, it’s not a very helpful one to have data about. I could probably show exercising 10 minutes a day, surfing Facebook or reading a book is more effective than doing nothing at all and would improve most people’s mood.

We ask for a higher standard from drug makers, and so I see little reason we shouldn’t be asking for an equivalent high standard from psychotherapy researchers.

And because the non-specific factors of different types of psychotherapy — such as the quality of the therapeutic alliance and relationship, empathy, being non-judgmental, etc. — appear to be powerful, you’d want to show that whatever technique or specific type of therapy you’re offering is more than these factors alone.

A Better Control Group in Psychotherapy Research

The best way to do this is to throw out the waitlist control group and replace it with a group of participants randomized to receive weekly check-ins with the equivalent of someone showing concern for the individual. This can be an individual one-on-one session, or a small group of participants.

It wouldn’t be therapy, because the person sitting with the participant isn’t a therapist and has no specific training in therapy. Maybe they’re a paid undergraduate student research assistant or a nurse practitioner (not a psychiatric nurse practitioner). Maybe instead of 50 minutes, they’re given only 20 minutes.

This kind of design would allow for the type of minimal study contact on a weekly basis that replicates the mechanics of psychotherapy, but with none of the supposed benefits of specific psychotherapy techniques.

Would it require a little additional money to run? Yes. But it would clearly demonstrate the benefits of the psychotherapy techniques under study more so than when compared to a wait-list control group alone.

References

Gallin & Ognibene (2012). Principles and practice of clinical research. Academic Press.