ATLANTA – Approximately 20% of cases of chronic low back pain in younger adults seen in primary care settings might be caused by spondyloarthritis, based on data from 364 patients aged 19-45 years. The findings were presented at the annual meeting of the American College of Rheumatology.

In the cross-sectional study, 77 of 364 patients (22%) met the diagnosis of axial spondyloarthritis on examination by a rheumatologist. The average age of the patients was 36 years, 43% were male, and the average duration of chronic low back pain was 9 years.

The diagnostic techniques included a detailed patient questionnaire about inflammatory back pain, physical examination and patient history; blood tests to assess C-reactive protein levels and the presence of HLA-B27 (a gene that has been linked to spondyloarthritis); and conventional and MRI images of sacroiliac joints. Two radiologists reviewed the images for the signs of inflammation and bone lesions that might indicate axial spondyloarthritis.

Fifty-two patients were diagnosed according to MRI criteria plus one additional spondyloarthritis feature. The other 12 patients were diagnosed according to a positive HLA-B27 test plus two additional spondyloarthritis features, Dr. Angelique Weel of Maasstad Ziekenhuis, Rotterdam, the Netherlands, said at a press conference.

In addition, 24 patients (6.6%) met the criteria for ankylosing spondylitis.

The results suggest that spondyloarthritis is underdiagnosed as a cause of chronic back pain in the general population. Dr. Weel recommended that primary care physicians suspect spondyloarthritis when they see younger adults with chronic back pain, and refer these patients to a rheumatologist if they suspect an inflammatory basis for the pain.

"We also tried to make a simple questionnaire for general practitioners, so they can determine which patient with chronic low back pain should be sent to a rheumatologist to investigate possible spondyloarthritis," she noted. Possible red flags from the standardized questionnaire include the response to NSAIDs and a family history of spondyloarthritis, Dr. Weel said.

"Of course, we need to validate these data in another population, and we also have to validate our referral tool [for general physicians]," she noted.

Dr. Weel said that she had no financial conflicts to disclose.

12/08/10  

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FROM THE ANNUAL MEETING OF THE AMERICAN COLLEGE OF RHEUMATOLOGY

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Major Finding: In 20% of patients first seen in primary care settings, axial spondyloarthritis was the cause of chronic low back pain.

Data Source: A cross-sectional study of 364 adults aged 19-45 years with chronic back pain.

Disclosures: Dr. Weel said that she had no financial conflicts.