BSIP / Science Source
The history and findings in this case are suggestive of axial psoriatic arthritis (PsA).
Psoriasis is a complex, chronic, inflammatory, immune-mediated disease that is associated with significant morbidity, reduced quality of life, and increased mortality. Approximately 7.4 million adults in the United States have psoriasis; worldwide, approximately 2%-3% of the population is affected. Patients with psoriasis frequently have comorbidities; PsA, an inflammatory, seronegative musculoskeletal disease, is among the most common. It is estimated that 25%-30% of patients with psoriasis develop PsA.
PsA is a heterogeneous disease. Patients may present with nail and skin changes, peripheral arthritis, enthesitis, dactylitis, and axial spondyloarthritis (SpA), either alone or in combination. Men and women are equally affected by PsA, which typically develops when patients are age 30-50 years. Like psoriasis, PsA is associated with numerous comorbidities, including cardiovascular disease, metabolic syndrome, obesity, diabetes, depression, uveitis, and anxiety.
PsA is a potentially erosive disease. Structural damage and functional impairment occurs within 2 years of initial assessment in approximately 50% of patients; as the disease progresses, patients may experience irreversible joint damage and disability. Axial involvement occurs in 25%-70% of patients with PsA; exclusive axial involvement is uncommon, occurring in 5% of patients. Common symptoms of axial PsA include inflammatory back pain (eg, pain that improves with activity but worsens with rest, morning stiffness lasting longer than 30 minutes). Some patients with axial involvement may be asymptomatic. If untreated, cervical spinal mobility and lateral flexion significantly decline within 5 years in patients with axial PsA. In addition, sacroiliitis worsens over time; 37% and 52% of patients develop grade 2 or higher sacroiliitis within 5 and 10 years, respectively. This highlights the importance of early identification and treatment of patients with axial PsA.
The diagnosis of axial PsA is confirmed by physical examination and imaging. Axial PsA characteristics, including sacroiliitis and spondylitis, are distinguished by the development of syndesmophytes (ie, ossification of the annulus fibrosis). PsA can be differentiated from ankylosing spondylitis by the asymmetric and frequently unilateral presentation of sacroiliitis and syndesmophytes, which frequently presents as nonmarginal, bulky, asymmetric, and discontinuous skipping vertebral levels.
Plain radiography, CT, ultrasound, and MRI are all useful tools for evaluating patients with PsA. MRI and ultrasound may be more sensitive than plain radiography is for detecting early joint inflammation and damage as well as axial changes, including sacroiliitis; however, they are not required for a diagnosis of PsA.
The treatment of axial PsA is based on international guidelines developed by the American College of Rheumatology/Spondylitis Association of America/Spondyloarthritis Research and Treatment Network, the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis and the Assessment of SpondyloArthritis International Society–European League Against Rheumatism. Treatment focuses on minimizing pain, stiffness, and fatigue; improving and preserving spinal flexibility and posture; enhancing functional capacity; and maintaining the ability to work, with a target of remission or minimal/low disease activity.
Medications for symptomatic relief include nonsteroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, and sacroiliac joint injections with glucocorticoids for mild disease; however, long-term treatment with systemic glucocorticoids is not recommended. If patients remain symptomatic or if erosive disease or other indications of high disease activity is observed, guidelines recommend initiation of a TNF inhibitor. Disease-modifying antirheumatic drugs, such as methotrexate, are not routinely prescribed for patients with axial disease because they have not been shown to be effective.
If symptoms of axial PsA are not controlled by NSAIDs, tumor necrosis factor (TNF) inhibitors are recommended. However, interleukin 17A inhibitors may be used in preference to TNF inhibitors in patients with significant skin involvement. In the United States, adalimumab, certolizumab pegol, golimumab, and infliximab are recommended over etanercept for patients with axial SpA in the presence of concomitant inflammatory bowel disease (IBD) or recurrent uveitis (although there is no evidence for golimumab) because etanercept has contradictory results for uveitis and has not been shown to have efficacy in IBD.
If patients fail to respond to a first trial of a TNF inhibitor, trying a second TNF inhibitor before switching to a different class of biologic is recommended by US guidelines. A Janus kinase inhibitor (tofacitinib) may be considered for patients who do not respond to TNF inhibitors.
Nonpharmacologic therapies (ie, exercise, physical therapy, massage therapy, occupational therapy, acupuncture) are recommended for all patients with active PsA.
Herbert S. Diamond, MD, Professor of Medicine (retired), Temple University School of Medicine, University of Pittsburgh; Chairman, Department of Medicine Emeritus, Western Pennsylvania Hospital, Pittsburgh, PA.
Herbert S. Diamond, MD, has disclosed no relevant financial relationships.
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