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Nearly 20% of patients with psoriasis also have psoriatic arthritis

Almost one in five patients with psoriasis worldwide also had psoriatic arthritis, with congruous results seen across many different statistical subpopulations, according to data recently published in the Journal of the American Academy of Dermatology.

“Despite the increasing recognition of [psoriatic arthritis] as a distinct disease, the lack of a widely accepted and validated case definition has yielded considerable variability in [psoriatic arthritis] prevalence estimates,” Farzad Alinaghi, MD, of the department of dermatology and allergy, Herlev and Gentofte Hospital, University of Copenhagen, Denmark, and colleagues wrote.

“Several observational studies have investigated the latter issue, but no meta-analysis has yet been performed to estimate the exact prevalence in patients with psoriasis,” researchers added.

Alinaghi and colleagues analyzed and reviewed 553 studies consisting of 976,408 patients with psoriasis, of whom 12,884 were either children or teenagers. Among the findings:

• 266 studies indicated an overall pooled psoriatic arthritis prevalence of 19.7% (95% CI, 18.5-20.9) in patients with psoriasis;
• 245 studies indicated a pooled psoriatic arthritis prevalence of 21.6% (95% CI, 20.3-22.9) in adults with psoriasis;
• 36 studies had data on psoriatic arthritis broken down by sex, indicating women with a 24% (95% CI, 20.1-28.1) prevalence and men with a 23.3% (95% CI, 19.4-27.5) prevalence;
• 47 studies revealed a pooled prevalence of 19.5% (95% CI, 17.1-22.1) in North America; and
• 21 studies indicated a pooled prevalence of 3.3% (95% CI, 2.1-4.9) among children and teenagers.

“Strengths of this study include the sheer number of studies, the focused inclusion of [psoriatic arthritis] patients rather than any type of arthritis, the liberal inclusion of various types of study populations and designs and lastly the inclusion of all types of diagnostic methods for [psoriatic arthritis].”

“On the other hand, our study was limited by the few studies from Africa and Australia complicating an accurate assessment of the prevalence of [psoriatic arthritis] among psoriasis patients in these regions. The exclusion of studies written in languages other than English, and a significant risk of publication-bias may also have affected our estimates. Furthermore, due to lack of available data we were not able to assess whether severity of psoriasis could explain the lower prevalence of [psoriatic arthritis] observed in children and in patients from Asia and Africa,” they wrote. – by Janel Miller

Disclosure: Alinaghi reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.