I’ve written previously about the evidence concerning hyperbaric oxygen therapy (HBOT). There are a few specific conditions for which there is reasonable evidence HBOT is a useful therapy. Unfortunately, it is becoming something of a fad treatment in veterinary medicine, and there are many claims and recommendations for HBOT that are not supported by real evidence. A new series of studies in humans from the Department of Defense has provided some additional useful evidence regarding this treatment.
Reported in the LA Times, these studies specifically examined HBOT as a therapy for symptoms of concussion in service members. The results so far consistently show no difference between HBOT and placebo, suggesting no real therapeutic benefit for the treatment. In one study, 72 patients were randomly assigned to HBOT or sham HBOT. Both groups showed a 30% improvement in symptoms reported on a patient questionnaire, with no difference between the real and placebo treatment. This is in agreement with two previous randomized clinical trials of HBOT of concussive symptoms, neither of which reported any benefit greater than placebo. The fourth, largest and most rigorous trial is still in progress.
What is especially interesting about these results is that both HBOT and placebo groups showed significantly more improvement than patients given standard care. This reflects the very similar results of acupuncture trials and studies of many other therapies which are no better than their sham placebo comparators but which appear to provide a benefit when compared to nothing at all or to minimal standard care.
Does this mean that placebo effects represent real healing? Absolutely not! Many studies have shown that placebo effects only change the perception of one’s symptoms and certain autonomic values (like blood pressure and heart rate) that are strongly influenced by psychological factors, not the objective measurements of one’s illness. What the results mean is that the ritual of care, particularly the more elaborate and involved the ritual is, improves how people feel even when the therapy does not actually change their physical condition.
It is useful to remind ourselves of this phenomenon for two reasons. First, it reinforces that we cannot believe the positive results seen in studies that do not have an effective sham or placebo treatment, because they cannot distinguish real improvement from the psychological effects of therapeutic rituals. Secondly, it gives human healthcare workers the opportunity to take advantage of such effects to improve patients’ experience of care. This should not be done by providing ineffective or fake therapies, of course. But there are many ways to generate a comforting therapeutic ritual while still providing scientific, evidence-based care.
In veterinary medicine, sadly, it is likely such rituals treat animal owners much more than our patients themselves (the caregiver placebo effect). Though this may have some value anyway, it raises the significant risk that we will convince ourselves and our clients we are helping their pets when we actually are not. Therefore, we in veterinary medicine have to hold our selves to the strictest standard of evidence we can to avoid fooling ourselves and our clients at the expense of our patients.