It is tempting, in research, to apply the normal rules of summation – where adding one treatment that you think is effective to another treatment that you think is effective should give you a combined treatment that is more effective than either. However, as Cormac Ryan from Glasgow Caledonian University points out, it does not necessarily work that way. Now, Cormac has written a post on his very interesting and just published trial, but he has written it in a culinary or perhaps grocery kind of way. So, I will explain it for you. Cormac likens pain biology education to an apple. He likens group exercise classes to another apple. Then he looks at what happens when you add two apples. Get it? Well read his blog post and I think you will:
1 apple + 1 apple ≤ 1 apple?
The aim of this single-blind pilot RCT was to investigate the effect of pain biology education and group exercise classes [EDEX/ two apples] (n=20) compared with pain biology education alone [ED/ one apple] (n=18) for individuals with chronic low back pain (CLBP). Primary outcomes measures were pain and function measured immediately before, after, and three months after, the intervention. Immediately post intervention there were more favourable results for the ED group (one apple > two apples). The effects leveled off at the three month follow-up (one apple = two apples). So, counter intuitively, why were two apples not better than one? It may be that EDEX patient’s perceived mixed messages – are the patients thinking “If the pain education is telling me my tissues are structurally fine and my back is strong, why are they sending me to exercise classes to rehabilitate my back”? So, clinically it may be important when combining interventions that the patient perceives the synergy between them, avoiding contradictory messages. Alternatively, perhaps the initial poorer outcome with two apples was due to prolonged biographical disruption. Biographical disruption occurs when an individual’s routine free-living daily life is interrupted and disorganised. Being in rehabilitation could be seen as a biographical disruption (Hammell, 2006, p. 115). Perhaps having more sessions over a longer period of time EDEX patients were held in this biographical disruption longer than they needed to be compared to their ED counterparts, slowing their recovery. This suggests that more intervention (apples) may not result in better outcomes.
Cormac Ryan has two first names. This would not be a problem except that his first name is not as obvious a first name as his second name is. Both names carry an air of intellectual prowess and it seems that in this particular situation, one apple plus another apple DO make more than one apple. Ryan, sorry, Cormac, is very well credentialed to run a trial like his – he did a Sports & Exercise Science degree at Limerick, a Masters in Physiotherapy at Queen Margaret University College Edinburgh and a PhD from Glasgow Caledonian University, where he currently teaches on the undergraduate and masters Physiotherapy programs. What is more he is a smashingly nice fellow. Clearly, he did not write this bio.
Hammell, K.W. (2006) Perspectives on disability and rehabilitation: contesting assumptions, challenging practice. Churchill Livingstone, Edinburgh.
Ryan CG, Gray HG, Newton M, & Granat MH (2010). Pain biology education and exercise classes compared to pain biology education alone for individuals with chronic low back pain: a pilot randomised controlled trial. Manual therapy, 15 (4), 382-7 PMID: 20359937
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