Two distinct clinical phenotypes have been described with regard to time-to-transition from onset of psoriasis to the development of psoriatic arthritis (PsA), in a study published in Seminars in Arthritis and Rheumatism. Researchers also noted that individuals with an earlier age at psoriasis onset or severe disease were more likely to have a delay in transition from psoriasis to PsA.

The researchers sought to identify demographic and clinical characteristics associated with transition time between onset of psoriasis and the development of PsA.

The retrospective, nested, population-based, case-control cohort study was conducted in Olmstead County, Minnesota. Adult patients with incident PsA, diagnosed between January 1, 2000, and December 31, 2017, were divided into 2 groups:


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patients with concurrent psoriasis and PsA diagnosis (within 1 year of each other) and patients with psoriasis prior to the development of PsA (>1 year). All patients who developed psoriasis after the onset of PsA were excluded from the study.

Patients with PsA were defined as those who met the Classification of Psoriatic Arthritis (CASPAR) criteria (ie, sensitivity of 91.4% and specificity of 98.7%). The date of fulfillment of the CASPAR criteria was considered to be the time of PsA onset. Onset of psoriasis was defined as the date that a confirmatory diagnosis was provided by a primary care physician, dermatologist, or rheumatologist.

A total of 164 patients with incident PsA were identified for the study. Of these, 6 had psoriasis onset after PsA (>1 year) and had a family history of psoriasis, and were excluded. A total of 158 patients were included in the final study population. The mean participant age was 46.3±12.0 years at diagnosis; 46% of the patients were women.

Of the 158 patients, 41% (n=64) had concurrent psoriasis and PsA, whereas in 59% (n=94) of participants, the onset of psoriasis occurred prior to the development of PsA. Median time from diagnosis of psoriasis to PsA incidence was 35.5 months, whereas the median estimated time from the onset of first psoriasis eruption to the onset of inflammatory joint pain was 2 years. Among patients with psoriasis prior to PsA, the median time from the diagnosis of psoriasis to PsA incidence was 118.5 months. Although the time from the onset of psoriasis to PsA increased by 3% per year between 2000 and 2017 in the subgroup of individuals with psoriasis that occurred prior to PsA, this trend did not achieve statistical significance (P =.09).

The estimated age at onset of first symptom of psoriasis (odds ratio [OR] per 10-year decrease, 1.63; 95% CI, 1.26-2.11), type of psoriasis as chronic plaque psoriasis (OR, 3.14; 95% CI, 1.07-9.19), and severity of psoriasis compared with mild disease (OR, 1.69; 95% CI, 0.84-3.40 for moderate psoriasis and OR, 3.65; 95% CI, 1.18-11.32 for severe psoriasis) were more likely to be reported in those with a psoriasis diagnosis

at more than 1 year prior to PsA incidence compared with those with a concurrent diagnosis of both conditions.

The researchers concluded, “This classification might have important implications for epidemiological studies on the natural history of psoriatic disease, and the characteristics related to delay may provide targets for PsA prevention in future studies.”

Disclosure: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures. 

Reference

Karmacharya P, Wright K, Achenbach SJ, et al. Time to transition from psoriasis to psoriatic arthritis: a population-based study. Semin Arthritis Rheum. Published online December 31, 2021. doi:10.1016/semarthrit.2021.12.013