Psoriatic arthritis

Enthesitis Is Less Common in Ankylosing Spondylitis

Patients with psoriatic arthritis have more entheseal damage compared with patients with ankylosing spondylitis (AS), according to results of a new analysis.

Patients with AS and psoriatic arthritis share similar immunological features focused on enthesitis. However, a strong association between psoriatic arthritis and preceding injury has also been identified.


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For this study, the researchers analyzed ultrasonography scans of 1640 entheses from 79 patients with AS and 85 patients with psoriatic arthritis, which were then used to calculate entheseal inflammation and damage scores.

Regression models were used to evaluate the effect of AS or psoriatic arthritis diagnosis on outcomes controlled for age, gender, body mass index (BMI), clinical enthesitis, HLA-B27, and use of anti-tumor necrosis factor (anti-TNF) therapy.

Multivariate analysis indicated that patients with psoriatic arthritis had 4.22 times more damage than patients with AS, despite similar inflammation among those treated with anti-TNFs. Difference in entheseal damage was 5.6 times higher in patients with psoriatic arthritis than AS who never received anti-TNF therapy.

Results showed correlations between inflammation and damage scores with BMI (r = 0.392; r = 0.320) and age (r = 0.308; r = 0.538). Men had higher inflammation scores than women (12.3 vs 8.9).

“On [ultrasound] assessment, [patients with psoriatic arthritis] have greater entheseal insertion damage scores compared with AS, suggesting potential differences in tissue repair, immunobiology, or response to injury at insertions,” the researchers concluded.

—Melinda Stevens

Alhussain FA, Gunal EK, Kurum E, et al. Greater magnitude of entheseal microdamage and repair in psoriatic arthritis compared with ankylosing spondylitis on ultrasound [Published online September 26, 2018]. Rheumatology.