The diagnosis for this case is psoriatic arthritis (PsA). The 2018 American College of Rheumatology/National Psoriasis Foundation guidelines offer current treatment recommendations for this condition. For patients with active PsA who are treatment-naive, treatment recommendations are:
- Tumor necrosis factor (TNF) inhibitors are preferred over oral small molecules (OSMs), interleukin (IL)–17 inhibitors, or IL-12/23 inhibitors
- OSMs are recommended over IL-17 inhibitors or IL-12/23 inhibitors
- Methotrexate is recommended over nonsteroidal anti-inflammatory drugs
- IL-17 inhibitors are recommended over IL-12/23 inhibitors
Treatment recommendations for patients with active PsA despite the use of OSMs are:
- Switching to a TNF inhibitor over another OSM, IL-17 or IL-12/23 inhibitors, abatacept, or tofacitinib
- Switching to an IL-17 inhibitor over another OSM, IL-12/23 inhibitor, abatacept, or tofacitinib
- Switching to an IL-12/23 inhibitor over another OSM, abatacept, or tofacitinib.
International groups, such as the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) and the European League Against Rheumatism (EULAR), have published treatment recommendations as well. These address both PsA and, to a lesser extent, psoriasis. The GRAPPA recommendations consider six domains of involvement (peripheral arthritis, axial disease, enthesitis, dactylitis, skin psoriasis, and nail psoriasis) and use a grid approach to account for various levels of disease activity and severity. The EULAR recommendations use an algorithmic approach that focuses mainly on musculoskeletal manifestations, specifically peripheral arthritis; manifestations, such as dactylitis, enthesitis, and skin and nail involvement, are considered separately.
Psoriasis precedes the onset of PsA in 60%-80% of patients (sometimes by up to 20 years but usually by less than 10 years); but in as many as 15%-20% of patients, arthritis appears before psoriasis. On occasion, arthritis and psoriasis appear simultaneously.
Patients with PsA are typically seronegative for rheumatoid factor and antinuclear antibody; antinuclear antibody titers in persons with PsA do not differ from those of age- and sex-matched controls. C-reactive protein may be elevated but is often normal. Lack of C-reactive protein elevation, however, does not mean that systemic inflammation is absent but rather indicates that a different type of systemic inflammation may be at play for those patients.
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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