What we've learned from the ATLAS study.
New light, and a few mysteries too.
Thanks for reading the 10th edition of my sciatica newsletter. This newsletter tracks my research into all things lumbar radicular pain!
Thank you to everyone who asked me a question in reply to last week's newsletter. I think there are about fifty submissions. It’s given me a good idea of what people want to know and quite a few of the questions had never occured to me before.
Going forward, the podcast will come out midweek. To avoid spamming everyone, I won't be emailing it out. This week's podcast was an audio version of a post I wrote 2 years ago called Wired Into Pain. It's my attempt at the history of the science of pain.
With the SCOPiC trial published recently, I thought it would be a good time to go back over some of the interesting things we have learned from the ATLAS study.
Between 2011 and 2013, a group of researchers from Keele University, led by Kika Konstantinou, recruited a cohort of patients with low back related leg pain from Stoke-on-Trent. The researchers called their study the ATLAS study, meaning Assessment and Treatment of Leg pain Associated with the Spine.
The 609 people in the cohort had a mixture of acute and chronic pain. They all received usual care, with 90% of them seeing a physio. Every member of the cohort who wanted one got an MRI, which ended up as 554 people.
We can learn all sorts of interesting things from the ATLAS study. With apologies to people who like nice round numbers, here are 14 things that struck me.
74% of people with low back related leg pain were diagnosed with sciatica (which is what the authors choose to call radicular pain). The rest were diagnosed with referred pain.
Of the people with sciatica, 60% had a "definite or possible" nerve root compression on their MRI. (Of the people with referred pain, it was 32%.)
People with nerve root compression didn't have worse symptoms and didn’t do worse over time.
Disappointingly, there was no difference in inflammatory biomarkers between those patients with sciatica and those with referred pain.
About four in ten people in the cohort had neuropathic radicular pain, as determined by pain questionnaire and clinical assessment. A reminder that radicular pain is not necessarily neuropathic. But, neuropathic pain is relatively common nonetheless.
Unexpectedly, people with neuropathic pain did not do much worse over time than people without neuropathic pain.
In the cohort as a whole, 55% of people reported improvement after one year. (Improvement was defined as 30% or more improvement in Roland Morris Disability Questionnaire.) At the risk of being redundant: this means 45% of people did not improve.
Most of the improvements in symptoms came in the first three months, with a plateau thereafter.
People who did worse over time had a combination of: more severe leg pain, pain below the knee, pain interfering with work or housework, and loss of sensation on clinical exam.
But, stratifying care according to those prognostic factors did not seem to make a difference in the SCOPiC trial.
A surprising, very strong indicator of improvement was myotomal weakness. People with myotomal weakness did better over time than those without. Perhaps it is because this indicates a large herniation, likely to resorb? It is hard to say what is going on here but it can be a point of reassurance for patients.
21% of patients had "atypical sciatica": They had intense pain in the leg with sensory loss indicating sciatica, but unusually their back pain was just as bad as their leg pain, and they did not have much neural 'tension' or pain when coughing or sneezing...
On the whole, patients with more severe pain did worse over time and vice versa. But one small group of 17 patients had severe pain and improved dramatically after about four months, just as everyone else was plateauing….
Finally, an interesting piece of qualitative research on "biographical suspension" also came out of the ATLAS study - but I have written about this elsewhere: 7 insights from patients’ experience of sciatica - and how to act on them.
That’s it for now! I feel like this list throws some light on radicular pain and also reminds us that this condition is still very mysterious… I’ve deliberately tried not to editorialise too much on some of the more surprising findings. Let me know what you think!
Til next time,
Tom
P.S. In the end, the double hurricane came to nowt for Houston. We are all safe, if not that comfortable (today was 98 degrees with 81% humidity)!
Great post Tom, thanks. In which article of the ATLAS-study can I find the cluster analysis and individualized charts?