Low back pain research: The vegetarian barbeque?

I’m not a vegetarian. Perhaps that understates the issue, I am a fundamentalist carnivore and the idea of a barbeque without sausages and burgers is to me an unconscionable aberration; an affront to common decency. Just be honest and call it a salad party….and then don’t post my invitation.

Just as the missing meat at a barbeque is a matter of personal concern to me, so some very well regarded back pain researchers have just published a discussion paper in the European Spine Journal suggesting that something vital is being ignored in most back pain research – the back itself. They suggest that with the rise of the bio-psycho-social model of low back pain we all forgot the “bio” and that research is generally not focusing on improving our understanding of spinal pathology. They then point out some errors of reasoning that may in part be to blame for this.

Their key points are as follows:

  • Just because possible spinal diagnoses do not seem to improve clinical outcomes does not mean that they are unimportant in understanding back pain.
  • You don’t necessarily need a “gold standard” diagnostic test to investigate new diagnostic approaches.
  • Just because some folk without back pain demonstrate pathological changes does not mean that such changes are universally unimportant to back pain.
  • Clinical guidelines dismiss the ability to diagnose back pain based on relatively weak evidence
  • Using diagnostic tests to facilitate research does not mean you are endorsing them for clinical practice
  • Ignoring the biological component based on the current evidence base is fallacious

I have sympathy for much of their case. In a very human way research questions tend to fit into popular paradigms and it is a fair observation that in the label “non-specific low back pain” seems to have lead to a collective acceptance that since current diagnostic approaches seem unsatisfactory we shouldn’t look for new ones, or try to refine the existing ones. It does not necessarily follow that a correct diagnosis will lead to better clinical outcomes, and neither does it follow that just because our existing diagnostic models are not great there is no spinal diagnosis to be made – we might be missing something important in the spine.

However I do feel that in stating their case some relevant evidence was not mentioned or too readily dismissed. For instance the authors argue that “almost no quality literature exists” looking at specific pathology seen on MRI as a predictor of the course or development of back pain. But I can think of a few studies that are worth a mention. Borenstein and colleagues recruited a group of 67 asymptomatic subjects who were subsequently followed up 7 years later. At the initial MRI scan 31% of participants demonstrated an identifiable abnormality of the lumbar disc or spinal canal. From the 50 who responded no association was seen between the incidence of disc or spinal canal pathology and the development or duration of low back pain. Similarly Jarvik et al. recruited 148 folk who reported no back pain and performed MRI scans at baseline and at 3 year follow up. 131 of this group were followed up of whom 123 had repeat MRI scans. The presence and course of any back pain was monitored at 6 monthly intervals. Over the study period MRI findings were found to change little and no association was found between new low back pain, disc degeneration or endplate changes, annular tears or facet joint degeneration. Finally Eugene Carragee’s group recruited 100 patients with mild persistent LBP without disability. Subjects underwent lumbar MRI and those who were willing underwent lumbar discography. Subjects were followed at 6 monthly intervals over a 5 year period. Again no association was found between any feature of MRI or discography and clinical outcome.

Now you couldn’t call this a wealth of data but these studies are prospective and I don’t think that they represent “almost no” data. They each have their strengths and weaknesses but their findings are reasonably consistent. The main issue is probably their size and lack of power to detect a relationship but they at least indicate that if a relationship is there it is probably pretty weak.

Regardless the authors make an important point: forgetting the spine in back pain research is likely to reduce our understanding of spinal pain. The current absence of evidence may not necessarily be evidence of absence and ignoring possible peripheral drivers of pain from the spinal tissues is just as undesirable as clinging to an old-school Cartesian view of back pain. You can bring your salad, your bread rolls, your ketchup and your cheese but a hamburger without meat is not really a hamburger.

Note to Aussie readers and colleagues – that does not mean I am endorsing the inclusion of pineapple or beetroot in a burger – clearly that is just plain wrong.

Addendum

It’s worth being clear that the paper and this blogpost are principally about back pain research, not clinical practice. There is no shortage of folk focusing on structural spinal problems clinically, both real and imagined.  My own personal view is that no treatment model yet has a strong basis for action in light of the existing evidence (for both diagnosis and efficacy).

About Neil

Neil OConnellAs well as writing for Body in Mind, Neil O’Connell is a researcher in the Centre for Research in Rehabilitation, Brunel University, West London, UK. He divides his time between research and training new physiotherapists and previously worked extensively as a musculoskeletal physiotherapist. He also tweets! @NeilOConnell

He is currently fighting his way through a PhD investigating chronic low back pain and cortically directed treatment approaches. He is particularly interested in low back pain, pain generally and the rigorous testing of treatments.

References:

ResearchBlogging.org

Borenstein DG, O’Mara JW Jr, Boden SD, Lauerman WC, Jacobson A, Platenberg C, Schellinger D, & Wiesel SW (2001). The value of magnetic resonance imaging of the lumbar spine to predict low-back pain in asymptomatic subjects : a seven-year follow-up study. The Journal of bone and joint surgery. American volume, 83-A (9), 1306-11 PMID: 11568190

Carragee,E., Alamin,T., Miller,J., Carragee,J. (2005). Discographic, MRI and psychosocial determinants of low back pain disability and remission: a prospective study in subjects with benign persistent back pain The Spine Journal, 5 (1), 24-35 DOI: 10.1016/j.spinee.2004.05.250

Hancock MJ, Maher CG, Laslett M, Hay E, & Koes B (2011). Discussion paper: what happened to the ‘bio’ in the bio-psycho-social model of low back pain? European spine journal PMID: 21706216

Jarvik JG, Hollingworth W, Heagerty PJ, Haynor DR, Boyko EJ, & Deyo RA (2005). Three-year incidence of low back pain in an initially asymptomatic cohort: clinical and imaging risk factors. Spine, 30 (13) PMID: 15990670