Print Page

Spondylitis Association of America Research Article Archive

Health research has high value to society. It can provide important information about disease trends and risk factors, outcomes of treatment, functional abilities, patterns of care, and health care costs and use. The different approaches to research provide complementary insights. Clinical trials can provide important information about the efficacy and adverse effects of medical interventions by controlling the variables that could impact the results of the study, but feedback from real-world clinical experience is also crucial for comparing and improving the use of drugs, vaccines, medical devices, and diagnostics.

Below you will find links to some of the studies that have contributed to our increased understanding of spondyloarthritis.

SAA receives no government funding and relies on the generous donations from individuals to create and maintain the programs and services aimed at improving the futures of the 2.7 million Americans affected by spondylitis.

Research Article Archive

The Epidemiology of Back Pain, Axial Spondyloarthritis and HLA-B27 in the United States

The concept of inflammatory back pain (IBP) evolved in the 1970s, coincident with the discovery of the HLA-B27 association with ankylosing spondylitis (AS), leading to the development of criteria to determine the presence of IBP. The concept of IBP and it relationship with AS and axial spondyloarthritis (AxSpA) has further evolved, and an instrument developed (the Spondylitis Association of America Back Pain Tool), which was further modified and field tested for use in the 2009-2010 National Health and Nutrition Examination Survey (NHANES). This has shown the frequency of chronic back pain to have risen to 19.4%, with nearly one-third having IBP. The prevalence of AxSpA has been defined at 1.0-1.4% and AS at 0.52-0.55%. The national prevalence of HLA-B27 in the U.S. is 6.1%, and intriguing data from NHANES 2009 suggest a decreasing frequency with increasing age. From this arise new questions and a work agenda ahead.

The Transition of Acute to Chronic Bowel Inflammation in Spondyloarthritis

Liesbet Van Praet, Peggy Jacques, Filip Van den Bosch and Dirk Elewaut


That gut and joint inflammation are linked in spondyloarthritis (SpA) has been recognized for almost three decades. Intriguingly, microscopic gut inflammation, which occurs frequently in patients with SpA, is an important risk factor for clinically overt Crohn’s disease and ankylosing spondylitis. This Review describes current insights into the underlying mechanisms that lead to chronic gut inflammation in patients with SpA. We propose that the development of chronic bowel inflammation in these individuals occurs through a transition phase, in which inflammation evolves from an acute into a chronic state. Our transition model implies that different cell types are involved at different stages during disease progression, with stromal cells having an important role in chronicity. In addition, deficient regulatory feedback mechanisms or genetically determined alterations in antigen presentation, endoplasmic reticulum stress, autophagy or cytokine signaling might also favor a transition from self-limiting acute inflammation to chronic inflammation. We anticipate that this transition phase might be an important window for therapeutic intervention.

The United States National Health and Nutrition Examination Survey and the Epidemiology of Ankylosing Spondylitis

Charles F. Dillon, MD, PhD and Rosemarie Hirsch, MD, MPH


Currently available U.S. population– based data for ankylosing spondylitis (AS), spondyloarthritis and inflammatory back pain (IBP) from the nationally representative U.S. National Health and Nutrition Examination Survey (NHANES) include both NHANES I(1971–1975) and NHANES II (1976 –1980) surveys. The pelvic radiographs obtained in NHANES I provided U.S. prevalence estimates for radiographic sacroiliitis, an important component of the AS case definition. AS and spondyloarthritis prevalences cannot readily be calculated from NHANES I survey data; however, IBP prevalence (Rudwaleit et al Criteria 7b) can be estimated from NHANES II. The NHANES II estimate for IBP is 0.8% of the adult population ages 25 to 49 years. The prevalence of IBP in the subset of persons with a history of a back pain episode lasting 2 or more weeks was 6.7%. The 2009 –2010 NHANES U.S. Inflammatory Back Pain/Spondyloarthritis survey is currently fielded


Theme picker

Stay Informed



Visit our careers page for available positions

Contact Us

Spondylitis Association of America

16360 Roscoe Blvd.  Ste. 100
Van Nuys, CA 91406


Information Requests

(800) 777-8189 U.S. only
or (818) 892-1616
*Please note: This is not a Crisis Hotline. If you are in a life-threatening crisis, please dial 911 for immediate help in the US. Please follow this link for crisis intervention resources.

Give With Confidence
Click to verify BBB accreditation and to see a BBB report for Spondylitis Association of America