Spondyloarthritis: 3 New Things

Aug 15, 2018

Similarities between ankylosing spondylitis and non-radiographic axial SpA, a caveat about positive MRI scans, and the impact of obesity on disease outcomes.

References1. Mease PJ, van der Heijde D, Karki C, et al. Characterization of patients with ankylosing spondylitis and non-radiographic axial spondyloarthritis in the US-based Corrona Registry. Arthritis Care Res. 2018 Feb 6. doi: 10.1002/acr.23534.2. de Winter J, de Hooge M, van de Sande M, et al. Magnetic resonance imaging of the sacroiliac joints indicating sacroiliitis according to the assessment of SpondyloArthritis International Society definition in healthy individuals, runners, and women with postpartum back pain. Arthritis Rheumatol. 2018;70:1042-1048. doi: 10.1002/art.40475.3. Fitzgerald G, Gallagher P, Sullivan C, et al. Obese axial spondyloarthropathy patients have worse disease outcomes [abstract 2508]. Arthritis Rheumatol. 2017;69(suppl 10). https://acrabstracts.org/abstract/obese-axial-spondyloarthropathy-patients-have-worse-disease-outcomes/.

The highlights of three new studies on axial spondyloarthropathies include: (1) the same types of treatment, such as anti-tumor necrosis factor therapy, are equally effective in ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis, which supports the suggestion they are part of a spectrum of disease; (2) the diagnosis of spondyloarthritis cannot be made solely on a positive magnetic resonance imaging (MRI) scan; and (3) obesity is an independent predictor of higher disease activity and worse function among patients with axial spondyloarthropathy.^1-3 Scroll through the slides for the latest findings and their clinical implications.

(Woman’s spine: ©SebastianKaulitzki/Shutterstock.com; MRI scan: ©Deymos.HR/Shutterstock.com; obese man: ©Ollyy/Shutterstock.com)

The first nationwide study to characterize patients with ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (SpA) in the United States shows patients with these two diseases share a comparable degree of disease burden and have similar treatment patterns in clinical practice.¹ Data from the Corrona Psoriatic Arthritis/Spondyloarthritis Registry show 407 adults with a diagnosis of axial spondyloarthritis, including 310 patients with AS and 97 with non-radiographic axial SpA. Both groups shared a similar disease burden, as reflected by comparisons of disease activity and function, quality of life, pain, fatigue, absenteeism, and work productivity loss.

The proportions of patients receiving prior biologic diseaseâmodifying anti-rheumatic drugs (DMARDs) were similar between patients with nonâradiographic axial SpA (74.2%) and AS (64.8%). Current DMARD use percentages were very similar (63.9% vs 61.3%, respectively).

Clinical Implications: The results show the importance of early diagnosis and initiation of appropriate therapy for both groups of patients. Clinicians should not hold off using effective therapy in non-radiographic axial spondyloarthritis in the belief that this disease is less severe.

A substantial proportion of healthy persons without current or past back pain have an MRI scan positive for sacroiliitis, but deep, extensive lesions are almost exclusively found in those with axial spondyloarthritis (SpA). A clinical study had 3 trained, blinded readers randomly score MRI scans of the sacroiliac joints in 172 people: 47 healthy individuals; 47 gender- and age-matched patients with axial SpA from the SPondyloArthritis Caught Early (SPACE) cohort with confirmed, positive MRI results; 47 age- and gender-matched patients with chronic back pain irrespective of MRI results; 7 women with postpartum back pain lasting several months; and 24 frequent runners.²

Virtually all (91.5%) of the patients with axial SpA had an MRI scan positive for sacroiliitis, as did nearly one-quarter (23.4%) of healthy volunteers and 6.4% of those with chronic back pain. Some 12.5% of runners and more than half (57.1%) of the women with postpartum back pain had a positive MRI scan. Deep bone marrow edema lesions were not found in healthy volunteers, patients with chronic back pain, or runners, but these lesions were found in 42 (89.4%) of 47 patients with scans positive for axial SpA and in 1 (14.3%) of 7 women with postpartum back pain.

Clinical Implications: “Sacroiliac MRI has become an important aid in diagnosing spondyloarthritis, since sacroiliac joint inflammation and damage are hallmarks of this disease. Unfortunately, physicians all too often pay too much attention to a positive MRI, and consider it a decisive feature in the diagnosis. We have learned that sacroiliac MRI can also be positive in unaffected, or healthy, individuals. This study was started in order to provide an estimate of positive sacroiliac MRI in the healthy population, so that we can better appreciate a positive MRI in the context of a patient presenting with symptoms of spondyloarthritis,” said lead author Robert LandewÃ©, MD, PhD, Professor of Rheumatology at the University of Amsterdam in the Netherlands.

Obese patients with axial spondyloarthropathy have higher disease activity, worse physical function, and lower quality of life. A cohort of 683 patients from the Ankylosing Spondylitis Registry of Ireland had standardized clinical assessments and structured interviews that provided patient-reported data.³ The patients had a mean age of 45.9 years and mean disease duration of 19 years; three-quarters of the patients were male and more than two-thirds of them were overweight or obese.

Patients with axial spondyloarthropathy who were overweight or obese had the disease for a longer time and had more comorbidities, especially hypertension and hyperlipidemia, than those of normal weight. Obese patients with axial spondyloarthropathy had significantly higher disease activity scores and worse physical function, spinal mobility, and quality of life than patients of normal weight or those who were overweight.

Clinical Implications: “Traditionally, we have a perception of patients with axial spondyloarthropathy being of normal or even thin body build. However, recent studies have indicated that this is not the case, and that obesity is prevalent in axial spondyloarthropathy patients,” said lead author Gillian Fitzgerald, MD, Rheumatology Specialist Registrar at St. James’s Hospital in Dublin, Ireland. “The negative consequences of obesity in the general population are well documented, with affected patients suffering greater morbidity and mortality. Research to date in axial spondyloarthropathy indicates that disease outcomes may be worse in obese patients.”