Monday, November 28, 2016

Group vs. Individual Cognitive Processing Therapy for Combat-related PTSD

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The only problem I have with Cognitive Processing Therapy is that  I wouldn't seek it out if I had PTSD.

So the results of this clinical trial have been published. A total of 268 combat veterans with PTSD were randomly assigned to receive either individual (one-on-one) or group CPT. At the end of 12 sessions, the veterans in the individual arm showed more improvement that those in the group arm (although half of them still had PTSD).

This study is certainly going to go onto the pile of evidence which supports the use of CPT with this patient population. It might do a little to reduce the VA's usual practice of placing 8 to 10 veterans in a room for 90 minutes with a masters-level therapist, versus the vastly more costly, but clinically superior approach of matching individual patients to highly skilled therapists. But I doubt it.

One problem, however, is just how weak this study actually is. Look at the main outcome measures -- the PCL and the BDI-2, two self-report checklists that patients can complete in under 5 minutes. You enter a study, take those two surveys, then do 12 sessions with a nice therapist, who has you then complete the same two surveys again. Even if you were mentally retarded or psychotic, you would know that your scores on those surveys are supposed to be lower than they were when you started. A huge part of the supposed efficacy in these studies are just demand effects -- giving the nice therapist a "tip," if you will.

There's an easy fix to this, and that is to use a real outcome measure, such as the MMPI-2 -- a 567 item True-False questionnaire that measures a wide range of psychopathology, not just explicit PTSD symptoms and obvious depression symptoms. The MMPI-2 also detects when patients are exaggerating or minimizing their symptoms, which you think would come in handy in a clinical trial. It measures PTSD and depression. About 90% of patients can complete it in 90 minutes or less.

So why not use it? Because there is absolutely no way that 12 sessions of CPT or any other "evidence-based" cognitive therapy is going to show any serious effect on combat PTSD veterans' MMPI scores after just 12 sessions. No way. MMPI scores are vastly more reliable than PCL and BDI scores, i.e., they are more stable over time. MMPI scores are more reflective of how the patient is really doing, and are far less susceptible to demand effects.

I don't know of any clinical trials that have used the MMPI as an outcome measure. I will take a look and see if I can find any. Using just the PCL and BDI-2 renders the studies clinically useless, in my opinion. I could run a study today that shows that reading Chinese restaurant menus lowers PCL and BDI-2 scores. Why? Because study participants are nice people and they don't want the researchers to look like idiots/fail at their jobs, so they help them by giving themselves lower scores after the treatment. This is a lot harder to do on the MMPI because it is not at all obvious which of the 567 items are measuring PTSD. Even if you did know which items measured PTSD, you might not be able to figure out whether to answer them True or False in order to raise or lower your score.

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