Applied Evidence

Could that back pain be caused by ankylosing spondylitis?

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It can often take years for patients with this condition to learn the true cause of their pain. But this guide to the work-up can help speed the diagnostic process.


› Evaluate all patients with back pain lasting > 3 months for inflammatory back pain features. C

› Treat all patients with confirmed or suspected axial spondyloarthritis with a trial of nonsteroidal anti-inflammatory drugs. A

› Recommend that all patients with back pain—including those with suspected axial spondyloarthritis—start an exercise program that includes both strength and aerobic activities. A

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series




A 38-year-old man presents to your primary care clinic with chronic low back stiffness and pain. You have evaluated and treated this patient for this complaint for more than a year. His symptoms are worse in the morning upon wakening and improve with activity and anti-inflammatory medications. He denies any trauma or change in his activity level. His medical history includes chronic insertional Achilles pain and plantar fasciopathy, both for approximately 2 years. The patient reports no systemic or constitutional symptoms, and no pertinent family history.

How would you proceed with his work-up?

Ankylosing spondylitis (AS) is a form of arthritis that primarily affects the spine and sacroiliac joints. It is the most common spondyloarthropathy (SpA)—a family of disorders that also includes psoriatic arthritis; arthritis associated with inflammatory bowel disease; reactive arthritis; and juvenile SpA.1 AS is most prevalent in Caucasians and may affect 0.1% to 1.4% of the population.2

Historically, a diagnosis of AS required radiographic evidence of inflammation of the axial spine or sacrum that manifested as chronic stiffness and back pain. However, the disease can also be mild or take time for radiographic evidence to appear. So an umbrella term emerged—axial spondyloarthritis (axSpA)—that includes both AS and the less severe form, called nonradiographic axSpA (nr-axSpA). While patients with AS exhibit radiographic abnormalities consistent with sacroiliitis, patients with early, or nr-axSpA, do not have radiographic abnormalities of the sacroiliac (SI) joint or axial spine.

In clinical practice, the distinction between AS and nr-axSpA has limited impact on the management of individual patients. However, early recognition, intervention, and treatment in patients who do not meet radiographic criteria for AS can improve patient-oriented outcomes.

The family physician (FP)’s role. It is not necessary that FPs be able to make a definitive diagnosis, but FPs should:

  • be able to recognize the symptoms of inflammatory back pain (IBP);
  • know which radiographic and laboratory studies to obtain and when;
  • know the Assessment of SpondyloArthritis international Society (ASAS) criteria3 that assist in identifying patients at risk for axSpA; and
  • know when to refer moderate- to high-risk patients to rheumatologists for assistance with the diagnosis.

FPs should have a high index of suspicion in any patient who has chronic back pain (> 3 months) with other features of SpA, and should pay special attention to young adult patients (< 45 years) who have IBP features.

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