Psoriatic Arthritis on the Rise

The primary comorbidity of psoriasis is psoriatic arthritis (PsA). The true incidence of PsA has long been an issue of debate. To estimate the incidence of PsA in patients with psoriasis and to identify risk factors for its development, Eder at al conducted a prospective cohort study involving psoriasis patients without arthritis at study entry that was published online in Arthritis & Rheumatology.

The investigators collected information from patients concerning lifestyle habits, comorbidities, psoriasis activity, and medications. The patients were evaluated at enrollment and annually. A general physical examination, assessment of psoriasis severity, and assessment for the development of musculoskeletal symptoms were conducted at each visit. A diagnosis of PsA was determined by a rheumatologist on the basis of clinical, laboratory, and imaging data; patients also had to fulfill the CASPAR (Classification Criteria for Psoriatic Arthritis) criteria (confirmed cases). The annual incidence of PsA was estimated using an event per person-years analysis.

The results from 464 patients who were followed for 8 years were analyzed. The annual incidence of confirmed PsA was 2.7 per 100 patients with psoriasis (95% CI, 2.1-3.6). Overall, 51 patients developed PsA over the course of the study and an additional 9 were considered suspect cases.

The following baseline variables were associated with the development of PsA in multivariate analysis: severe psoriasis (relative risk [RR], 5.4; P=.006), low level of education (college/university vs high school incomplete: RR, 4.5; P=.005; high school education vs high school incomplete: RR, 3.3; P=.049), and use of retinoid medications (RR, 3.4; P=.02). In addition, psoriatic nail pitting (RR, 2.5; P=.002) and uveitis (RR, 31.5; P<.001) were time-dependent predictors for PsA development.

The authors concluded that the incidence of PsA in patients with psoriasis was higher than previously reported. Possible factors for this finding might include differences in patient recruitment as well as self-reported PsA diagnoses.

What’s the issue?

This prospective analysis is interesting. The incidence of PsA was higher than reported. It reinforces the need for continual evaluation of joint symptoms in patients with psoriasis, even if they have had psoriasis for many years. How will this analysis impact your evaluation of psoriatic patients?

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