Risk for osteoarthritis (OA) is significantly higher among patients with psoriatic arthritis (PsA) compared with those with psoriasis and the general population, according to study results published in the Journal of Rheumatology.

The objective of the current study was to report on the risk for OA in patients with PsA compared with those with psoriasis and the general population.

Researchers used data from the Clinical Practice Research Datalink, an electronic healthcare database of patients in the United Kingdom primary care. Adults diagnosed with PsA between January 1, 1998, and December 31, 2014, were included in the current study. Cases of PsA were matched with those of a general population cohort that included patients without psoriasis or inflammatory arthritis at baseline, and with cases of psoriasis that included patients with psoriasis but without any other inflammatory arthritis. The primary outcome was a diagnosis of OA at any site.


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The study sample included 6783 patients with PsA who were matched with 27,132 control participants from the general population and 27,132 patients with psoriasis (median age in all groups, 49 years; 49.05% men in all groups). At baseline, the prevalence of OA was 22.1% in the PsA group, 12.5% in psoriasis group, and 11.0% in the general population group.

A total of 259 of 1497 patients (17.4%) with PsA and OA were diagnosed with OA within 12 months before the PsA diagnosis, and 420 (28.1%) were diagnosed within 2 years before the PsA diagnosis. Approximately half the number of patients with PsA received an OA diagnosis more than 5 years before their diagnosis of PsA.

Risk for OA diagnosis was significantly higher among patients with PsA, compared with those with psoriasis (relative risk, 1.68; 95% CI, 1.46-1.93) and the general population (relative risk, 1.86; 95% CI, 1.62-2.14). In the sensitivity analyses, the researchers observed risk for OA was reduced to a 55% and 39% increased risk, based on OA diagnoses starting at least a year after the index date. For site-specific OA diagnosed and recorded after the index date, a small increase was observed in OA of the hand/wrist and OA of the spine in the PsA vs general population cohort.

The study had several limitations, including missing data on body mass index, lack of data on exposure to biologic therapy, and potential detection and referral bias.

“This study has demonstrated an increased risk [for] OA in patients with PsA compared [with] patients with psoriasis and those in the general population after adjusting for [body mass index],” the researchers concluded.

Reference

Charlton R, Green A, Shaddick G, et al. Risk of osteoarthritis in an incident cohort of people with psoriatic arthritis: a population-based cohort study. J Rheumatol. Published online, November 15, 2020. doi:10.3899/jrheum.200564