I read "Usefulness of Posture Training for Patients With Temporomandibular Disorders" by Edward F. Wright, D.D.S., and colleagues (February JADA), and, in my opinion, the methodology does not support the conclusions reached in the article.
Perhaps I may provide the analogy that will, I believe, more clearly explain my disquiet about the methodology used by Wright and colleagues.
If one were to investigate the efficacy of a new drug in the treatment of arthritis, one could certainly take a group of patients who are matched for sex, age and clinical features and divide them into two groups. One group would review the new drug, the dosage recommended and so on. The other group would be getting a similar drug—both in size and color and frequency of usage—as the people in the treatment group.
If the physicians in the trial knew which drug was the effective one, they could expect approximately one-third of the patients to do well on the placebo. Evidence has shown that if the doctors did not know which patients were getting the effective drug and which were getting the placebo, the beneficent effects could reach as high as two-thirds of the patients in the control group.
After three, four or six months, to be sure that the efficacy of the new drug was really present, one could switch the trial and now put those who had been on the drug onto the placebo and vice versa. To be sure, there may be some problems in that the effects of the intended drug may have ameliorated some of the arthritic conditions such that there is an even better score than those who now go on to the control drug, having completed the course of treatment on the trial drug. This could be taken into consideration.
The reason the patients on the placebo drug do so well is not known, but no doubt part of reason is the hope, expectancy and anticipation that the drug they’re getting is an effective one. This is all so very well known that it makes it unnecessary to argue the case for placebo.
In the article, Wright and colleagues mention that they did consider putting the control group through the sham posture instruction but then decided not to because they may have developed a greater awareness of their posture, thus creating the treatment effect.
But if the sham treatment had not really included the special instructions that were thought to be of help and just involved some simple massage of the lower back or the shoulders or some other instruction, at least it would have meant that these people were getting some sort of contact and follow-up and interest in their care.
Furthermore, at the end of three or four months, the groups should have been switched. We are told that the control group did get physiotherapy after the end of the experiment, but we’re never told what the effects of that were.
It would appear that there was an initial meeting with the physiotherapist; then another after a week. At the end of four weeks, the subjects returned again, making it a total of three visits. We’re told that compliance ranged between 45 percent to 75 percent (I realize that is compliance with the practices that the people were supposed to do daily) and "no significant correlation between improvements and TMD symptoms and reported compliance." What this points out to me is that it would be more important to have put the control group through some sham physiotherapy exercises.
All the follow-up measurements were taken at the end of four weeks, after the start of the posture training exercises. We are not told how long a period the improvement in the TMD symptoms lasted.
It seems to me it wouldn’t have been difficult to have done even a phone follow-up six months later to see whether the patients were still maintaining their posture exercises, or whether after dropping the posture exercises the TMD symptoms were still in abeyance or had returned.
It may well be that Wright and colleagues possess the answers to a lot of these questions, but unfortunately, they were not included in their article. I would be grateful to you if you would ask them to respond to some of these points.
