Monday, November 28, 2011

Ankylosing Spondylitis – some shattered myths?

One should thinks with all the studies and publications, myths about ankylosing spondylitis should be shattered, but in fact these myths are still around interfering with proper diagnosis, early diagnosis, and adequate therapy. Despite suffering from inflammatory back pain it still may take years for patients to have a consultation with a rheumatologist.

Most people encounter some back during their lives. So most people orthopedic physicians see have common back pain. If the pain stays, maybe HLA B27, a genetic marker ist tested – some physicians even test HLA B27 several times – well that’s sending someone multiple times to the ophthalmologist asking if the eyes are still blue. OK, it’s a genetic marker – it won’t change. One test is enough.
Myth: if you don’t test positive for HLA B27, it cant’t be ankylosing spondylitis.
Wrong! If you test negative, it still may be ankylosing spondylitis, if you test positive for inflammatory back pain and more.
Myth: if you test positive for HLA B27, it is ankylosing spondylitis.
Wrong again! If you test positive, it still may be common back pain, if you test negative for inflammatory back pain and more.
Don’t think – that’s impossible - as it is daily reality. The point is doing a very helpful lab test (HLA B27) to strengthen your hypothesis, it might be ankylosing spondylitis, when you look at someone suffering from inflammatory back pain. Or you call for the lab to do your work, coming to a diagnosis in someone suffering from persistent non-inflammatory back pain, in which HLA B27 isn’t very helpful.
Are there hints, if it is inflammatory back pain? Yes, there are. This sort of back pain starts in the younger than 40 years, mostly in adolescents or young adults. The pain starts slowly and increases over time; whereas disc hernation of fracture have an acute onset of pain. Pain lasts longer than three months. Suffering from inflammatory back pain have an impact on sleep, most people wake up during the night, especially the second half of the night. Moving around not rest alleviates pain. And there’s morning stiffness. Localization is the very low back. So you can reach very far by simply taking an accurate history. Who said it before? Ask the patients, they have all the data, but you have to ask the right questions to get the answers you need.
Having ascertained inflammatory back pain, you still are far away from a proper diagnosis, but you can increase the likelyhood by taking more facts into account. Inflammamatory back pain has a LR (likelihood ratio) of 3.1; enthesitis has a LR of 3.4; peripheral arthritis has a LR of 4.0; dactylitis has a LR of 4.5; acute anterior uveitis has a LR of 7.3; positive family history has a LR of 6.4; good pain reduction following NSAIDs has a LR of 5.1; elevated inflammatory makers like CRP od ESR have a LR of 2.5; HLA B27 has a LR of 9.0 (here you see, at the right time it’s a very valuable parameter); MRT has a LR of 9.9 [Rudwaleit M. et al. Ann Rheum Dis 2004; 63: 535 - 543; Rudwaleit M. et al. Arthritis Rheum 2005; 52: 1000 – 1008]. If you check all these, multiply the LRs, and the product is above 200, the probability is above 90% that is ankylosing spondylitis. For chronic low back pain the probability for ankylosing spondylitis is about 5%.
To be continued …

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