若有chronic inflammtory back pain & x-ray sacroilitis就必須要高度懷疑此病了。血中HLA-B27不一定需要升高。
A patient with chronic inflammatory back pain and evidence of x-ray changes of sacroiliitis has a very high likelihood of having AS
近日一位門診病人，疑似免疫性引起的關節炎而轉介，一家醫院免疫風濕科認為非免疫性問題，家屬因故再轉診台大免疫風濕科認為是免疫引起，而開始給予類固醇等藥物治療。
免疫方面的疾病，有種種的臨床表現，常不能單由一項抽血結果來斷定，追蹤觀察有時也是必要的。
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SUMMARY AND RECOMMENDATIONS
Diagnosis of ankylosing spondylitis (AS) can be aided by evaluating the parameters in the Modified New York Criteria for Ankylosing Spondylitis, the ASAS classification criteria for Axial Spondyloarthritis, and also an algorithm (algorithm 1A-B). (See 'Diagnosis' above and 'Criteria used for classification and diagnosis' above.)
A thorough medical history, physical examination, and selected laboratory and imaging tests are used in diagnosis of AS and in the exclusion of other disorders considered in the differential diagnosis. (See'Diagnosis' above and 'Differential diagnosis' above.)
A patient with chronic inflammatory back pain and evidence of x-ray changes of sacroiliitis has a very high likelihood of having AS. (See 'Diagnosis' above.)
Patients may be diagnosed with axial spondyloarthritis prior to developing plain radiographic features of sacroiliitis, if they have sacroiliitis demonstrated by MRI or if they are HLA-B27 positive and have one to two additional features of spondyloarthritis, respectively, such as an elevated CRP and a good response to NSAIDs. (See 'Criteria used for classification and diagnosis' above.)
A therapeutic trial of antiinflammatory doses of an NSAID (eg, two weeks of naproxen 500 mg three times daily or diclofenac 150 mg daily) may aid in diagnosis. A substantial reduction in pain and stiffness with this regimen supports an inflammatory etiology of back pain and stiffness. (See 'Response to NSAIDs' above.)
Patients who have clinical features suggestive of AS but who lack diagnostic radiographic changes may eventually develop typical AS. Follow-up observations of patients suspected of SpA are required. (See'Diagnosis' above.)
The SpA features used in the ASAS classification criteria of axial SpA include:
- Inflammatory back pain (see 'Inflammatory back pain' above)
- Arthritis — diagnosed clinically by a physician
- Enthesitis — diagnosed clinically by a physician
- Uveitis — past or present anterior uveitis, diagnosed by an ophthalmologist
- Dactylitis — diagnosed by a physician
- Psoriasis — diagnosed by a physician
- Inflammatory bowel disease (IBD) — Crohn’s disease or ulcerative colitis diagnosed by a physician
- Good response to NSAIDs (nonsteroidal antiinflammatory drugs) — back pain becomes either absent or much better 24 to 48 hours after starting a full dose of NSAID
- Family history of SpA — presence in first-degree or second-degree relatives of any of the following: AS, acute uveitis, reactive arthritis
- HLA-B27-positivity
- Elevated CRP — above the upper limit of normal
The sensitivity and specificity of this set of criteria are 83 and 84 percent, respectively, when expert opinion is used as the “gold standard.
HLA-B27是否一定要positive ?
- HLA-B27 testing — All patients suspected of AS should be tested for HLA-B27 [3,6,9,10]. Among Caucasians, HLA-B27 is present in 95 percent of those with AS but only in about 8 percent of the general population, and the prevalence of AS in the HLA-B27 positive population is only about 5 percent. Thus, positive testing for HLA-B27 alone is not diagnostic.
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