Chronic lower back pain may be linked to axial spondyloarthritis: Research

Chronic lower back pain may be linked to a recently defined form of inflammatory arthritis known as axial spondyloarthritis, according to research presented this week at the American College of Rheumatology Annual Scientific Meeting in Atlanta.

Spondyloarthritis is the overall name for a family of inflammatory rheumatic diseases—including ankylosing spondylitis—that can affect the spine and joints, ligaments and tendons. These diseases can cause fatigue and pain or stiffness in the back, neck, hands, knees, and ankles as well as inflammation of the eyes, skin, lungs, and heart valves. While there is no course of prevention at this time, early treatment by a rheumatologist can reduce discomfort and loss of functionality.

Chronic lower back pain is one of the most common pain syndromes with an unknown cause. Studies looking at chronic lower back pain have reported that a small percentage of these patients may have ankylosing spondylitis (a diagnosis that requires the development of changes on an X-ray and is therefore typically diagnosed as many as 10 years after symptoms arise). Because treatment of spondyloarthritis (including ankylosing spondylitis) may be most successful when the condition is diagnosed early, disease criteria for axial spondyloarthritis that allow for a diagnosis in the absence of radiographic changes have recently been published by the Assessment of Spondyloarthritis International Society, allowing for earlier diagnosis and institution of therapy.

Researchers recently set out to determine the prevalence of this rheumatic disease in people being seen by their primary care physicians for chronic lower back pain. Additionally, researchers aimed to assess the value of the clinical tests primary care physicians use to evaluate chronic lower back pain as well as the questionnaires about inflammatory back pain completed by patients when seeking help for this painful condition.

The researchers studied 364 primary care patients of whom 43 percent were male, with an average age of just over 36 years, and who had been experiencing chronic lower back pain symptoms for an average of nine years. Participants were identified through their primary care physician medical records, were asked to complete a questionnaire detailing inflammatory back pain, received a full physical examination by a rheumatologist, and their blood was tested to assess HLAB27—a gene associated with spondyloarthritis—and C-reactive protein - a blood test of inflammation.

X-rays and MRIs were taken of each participant's sacroiliac joints (two joints that help make up the pelvis) and scored by two radiologists for the presence of inflammation and/or structural bone lesions typical axial spondyloarthritis.

The researchers diagnosed 77 participants (21.5 percent) with axial spondyloarthritis using the ASAS criteria; 52 were diagnosed with an MRI, 28 with X-ray and the presence of one other spondyloarthritis symptom, and 12 were diagnosed with a positive HLAB27 and two other spondyloarthritis symptoms. In all, 6.6 percent of the participants were diagnosed with the more stringent diagnosis of ankylosing spondylitis, which requires the presence of more advanced X-ray changes.

Of the participants seeing their primary care physicians for chronic lower back pain, the prevalence of spondyloarthritis was strikingly high. By using the new ASAS criteria, which aids in early diagnosis and treatment of the disease before structural bone lesions are present, three times as many patients were diagnosed as compared to the currently accepted criteria using conventional X-ray alone. Adding HLAB27 increased the likelihood of diagnosis of spondyloarthritis by 68 percent, and using X-rays increased the likelihood by 75 percent.

"The study confirms that there is a direct link between chronic lower back pain and spondyloarthritis," says Angelique Weel, PhD, MD; a rheumatologist at the Maasstadziekenhuis Rotterdam and an investigator in the study. "Such patients diagnosed by primary care physicians could be helped early in their disease by referral to a rheumatologist."