How is Psoriatic Arthritis diagnosed?

PsA is diagnosed by a rheumatologist assessing symptoms, performing a physical examination of the joints, and reviewing medical and family history¹. Blood tests and analysis of joint fluid can show inflammation and rule out other diagnoses¹. The rheumatologist may also do X-rays and in some cases, MRI scans to assess joint damage and soft tissue inflammation¹.

If PsA is suspected in an individual, their healthcare professional should promptly refer them to a rheumatologist. Healthcare professionals may also need to work together with experts in PsA, particularly when patients have common conditions that occur alongside PsA, such as psoriasis. Dermatologists should proactively monitor patients with psoriasis for signs of joint or arthritic involvement, to help with early detection of PsA².

Early diagnosis of psoriatic arthritis

Early referral and diagnosis are essential in PsA. Delayed diagnosis of PsA results in worse physical function^3,4. Even a six-month delay can result in worse outcomes for patients, with more joint erosion and damage⁵, and an increased frequency of comorbidities (other medical conditions that occur at the same time as the primary diagnosis)⁵. These can include obesity, cardiovascular disease, and depression⁵.

Infographic of body parts affected by PSA

Conditions that can resemble psoriatic arthritis

PsA may share features with other types of spondyloarthritis, and with osteoarthritis and rheumatoid arthritis. Features that suggest PsA rather than other conditions are joint erosion seen on X-ray, synovitis (inflammation of the joint linings) seen on power doppler ultrasound, and a personal or family history of psoriasis⁶. Patients with PsA are less likely to have autoantibodies (antibodies made against the body’s own proteins) called rheumatoid factor and anticitrullinated protein antibodies⁶. These antibodies are typically associated with rheumatoid arthritis⁶.

Comorbidities of psoriatic arthritis

People with PsA have a higher risk of developing inflammatory conditions outside the joints, including inflammatory bowel disease, uveitis (eye inflammation), depression, cardiovascular diseases, and metabolic syndrome (a grouping of high blood pressure, high blood sugar, and obesity)¹.

References

Gladman D, Ritchlin UpToDate Patient education: Psoriatic arthritis (Beyond the Basics) 2024 [Available from: https://www.uptodate.com/contents/psoriatic-arthritis-beyond-the-basics#H1.
Mease PJ, Armstrong Managing Patients with Psoriatic Disease: The Diagnosis and Pharmacologic Treatment of Psoriatic Arthritis in Patients with Psoriasis. Drugs. 2014;74(4):423-41.
Tillett W, Jadon D, Shaddick G, Cavill C, Korendowych E, de Vries CS, et Smoking and delay to diagnosis are associated with poorer functional outcome in psoriatic arthritis. Ann Rheum Dis. 2013;72(8):1358-61.
Ocampo DV, Gladman Psoriatic arthritis. F1000Res. 2019;8. Faculty Rev-1665.
Haroon M, Gallagher P, FitzGerald Diagnostic delay of more than 6 months contributes to poor radiographic and functional outcome in psoriatic arthritis. Ann Rheum Dis. 2015;74(6):1045-50.
Ruta S, Jaldin Cespedes R, Cuellar L, Mareco J, Aguerre D, García Salinas Psoriatic Arthritis: Differential Features at the Time of Clinical Presentation in a Large Cohort of Patients with Polyarthralgia. Eur J Rheumatol. 2023;10(1):12-7.