How to spot spondyloarthropathy.
Spondyloarthropathy is a tricky word to pronounce, but it can be even trickier to diagnose.
As Doctors, we often get it wrong – sometimes even as rheumatologists.
Didn’t we all learn about ankylosing spondylitis during our years of medical education? Yet sadly cases frequently go undiagnosed and untreated.
Might the outdated textbook, stereotypical black and white photo sequence of the aging man with A.S. (becoming more bent over as his disease progresses) be blinding us to everyday cases of inflammatory back pain?
Why does all this matter?
Ankylosing Spondylitis is just one of the spondyloarthropathys (SpA), The others include reactive arthritis, the kinds related to psoriasis, eye and inflammatory bowel disease, and a particularly mean form that afflicts youngsters.
All of them can cause long term structural damage, pain and disability. The structural changes (bone formation and the ‘ankylosing’ of joints) are irreversible, which basically means we need to sniff it out, and shut it down, ASAP.
So, how can we get better at spotting A.S.?
Firstly, try to keep an open mind. Not everyone with low back pain has ‘poor desk posture’ which needs a dose of Pilates.
We need to ask more questions.
Is the patient waking up in discomfort in the later hours of the night?
Do they have buttock pain which ‘moves around’?
Do they feel better when they hit the gym, but not better when they rest?
Does it take them a good while to ‘thaw’ out that morning stiffness?
In the current climate of discouraging excessive imaging and investigations, how do we know when it is appropriate to investigate? Firstly, it’s fair to say, that when investigation (and by that I mean MRI) happens, it needs to be the full enchilada. You need to image the whole spine and pelvis. Sacroiliac joint imaging on its own ‘aint enough.
Given that, that seems like an awful lot of imaging, when should we act?
Thankfully, some noble folk (namely Braun et al. Rheumatology 2013; 52:1418-24) have given us some excellent guidance. Rather than having a half-hearted bash at it, they are recommending that we simply refer the patient to a Rheumatologist with an interest in ‘ankyspondy stuff, in the following situations:
Firstly, ask the patient how old they are. If they are 45 years or younger, you get to ask them three more questions.
Question ‘A’ is, ‘do you have any buttock pain’?
Question ‘B’ is ‘is your discomfort made better when you move or exercise’?
Question ‘C’ is ‘have you ever had psoriasis’?
If the patient answers ‘yes’ to two or more of the A/B/C questions, you should refer them to the whizz kid rheumatologist.
If the patient answers ‘yes’ to only one or ‘no’ to all of the A/B/C questions, you should send them for an HLA B27 blood test.
If the HLA B27 blood test then comes back as positive, it’s a trip to the rheumatologist.
Note that there is no mention of any measuring of body angles, ordering of x-rays, or sending for ESR & other ‘serum rhubarb’ blood tests. Sweet.
How reliable is this little screening?
Well, it’s about 80.4% sensitive, and 75.4% specific for picking up A.S. In other words, it’s pretty useful!
So. The next time a patient sits in your room and tells you they have a pain in the bum, you have the potential to really make a difference in their life.
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