One in 5 Young Adults with Chronic Lower Back Pain Actually Had Spondyloarthritis

Atlanta—As many as 20% of patients treated by primary care physicians (PCPs) for chronic lower back pain may actually have spondyloarthritis and should be referred to a rheumatologist for diagnosis and treatment, according to a cross-sectional study presented at the ACR meeting. Until recently, spondyloarthritis could not be diagnosed at an early stage, but early diagnosis is now possible using serum assays to detect the presence of the human leukocyte antigen (HLA) B27 gene and C-reactive protein (CRP) without x-rays. Spondyloarthritis is treatable at early stages with nonsteroidal anti-inflammatory drugs (NSAIDs) and biologic therapy, but treatments are far less effective at later stages, making early diagnosis imperative. “One in 5 people between the ages of 20 and 45 who are diagnosed with chronic lower back pain were found to have spondyloarthritis. This is the age of disease onset, but it has been difficult to diagnose the disease early with conventional criteria,” explained senior author of the study, Angelique Weel, MD, PhD, Maasstadziekenhuis, Rotterdam, the Netherlands. Primary care patients with chronic lower back pain were identified from medical records by the International Classification of Primary Care code L03. All patients completed questionnaires provided by their PCP and underwent a complete history and physical examination by a rheumatolgoist. Blood samples were assessed for the presence of HLA B27 and CRP. Conventional x-rays and magnetic resonance imaging (MRI) of sacroiliac joints were obtained and then scored by 2 experienced radiologists with no clinical information about patients. Modified New York Criteria and MRI defined radiographic sacroiliitis according to Assessment of SpondyloArthritis International Society (ASAS) recommendations. The diagnosis of definite ankylosing spondylitis was made according to ASAS criteria. Of 364 patients enrolled in the study, 43% were male, and the average age was 36.3 years. Patients had been experiencing symptoms of chronic lower back pain for an average of 9 years. Seventy-seven patients (21.5%) were diagnosed with ankylosing spondylitis using ASAS criteria; 52 were diagnosed by MRI criteria and 1 other feature of the disease; and 12 were diagnosed by a positive HLA B27 test plus 2 other features of ankylosing spondylitis. Using the new ASAS criteria, which aids in early diagnosis and treatment of the disease before bone lesions develop, increased the diagnostic yield by 3 times compared with the currently accepted criteria using conventional x-ray alone, Dr. Weel said. Twenty-four patients (6.6%) were identified by more stringent criteria, which require the presence of more advanced changes on x-ray, and 75% of these patients also fulfilled ASAS criteria. The addition of HLA B27 further increased the likelihood of diagnosis of spondyloarthritis by 68.3%, and using x-rays increased the likelihood of diagnosis by 75.0%. Patients with a good response to NSAID therapy and those with a family history of arthritis are more likely to have spondyloarthritis and should be referred to a rheumatologist, Dr. Weel said. Responses to questions that suggest referral to a rheumatologist is advisable include pain during the night (when immobile), morning stiffness, and disappearance of pain with exercise. “A goal of our study was to develop a simple tool that PCPs can use in patients with chronic lower back pain to discriminate which patients might have spondyloarthritis and should be referred to a rheumatologist. We need to validate the questions that were found to discriminate between chronic lower back pain and spondyloarthritis in this study before we can tell PCPs to use them,” Dr. Weel stated.