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.
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.
Gallin & Ognibene (2012). Principles and practice of clinical research. Academic Press.
Grohol, J. (2018). Why Waitlist Control Groups in Psychotherapy Research Studies Suck. Psych Central. Retrieved on June 3, 2020, from https://psychcentral.com/blog/why-waitlist-control-groups-in-psychotherapy-research-studies-suck/