35% of PsA Patients Suffer from Clinical Enthesitis

January 23, 2017

Clinical enthesitis is a common condition for some psoriatic arthritis patients who are disproportionately affected by inflammation, particularly of the Achilles tendon, plantar fascia and lateral epicondyle.

A study published in Arthritis Care & Research shows that 35 percent of patients with psoriatic arthritis have clinical enthesitis.

In psoriatic arthritis, inflammation - or enthesitis  - occurs at the Achilles tendons, lateral epicondyle, joint capsule fibers or plantar fascia. It can lead to structural changes causing cystic and erosive reactions with periostitis, the development of spurs and/or syndesmophytes leading to pain and disability.

Little is known about clinical enthesitis in psoriatic arthritis patients, but it is known to be associated with a higher body mass index, more actively inflamed joints and a younger age.

In this study, which was led by Dafna Gladman, M.D., of the University of Toronto, researchers examined the prevalence, incidence, characteristics, disease associations, risk factors and outcomes of psoriatic arthritis patients with enthesitis.

The study included 803 patients who were treated at a tertiary care psoriatic arthritis clinic at the University of Toronto between 2008 and 2014.

At each visit, patients were assessed clinically and given a physical exam to assess issues including active inflammation, clinically damaged joint counts, spinal mobility measures, and psoriasis area and severity. Enthesitis was defined as the presence of at least one tender entheseal site out of 18 and was based on the SPondyloArthritis Research Consortium of Canada (SPARCC) enthesitis index.

Of 803 patients in the study, 281 patients, or 35 percent, had enthesitis. In most cases, enthesitis lasted 7.5 months (range: 4.5 months - 5.5 years). Of 227 (80.1%) patients with enthesitis who were followed at more than one visit, it resolved in 215 (95%), of whom 197 patients were treated with medications. However, most patients (139, 70.5%) improved without changing treatment.

Most patients had one (48.4%) or two (32.2%) tender entheseal sites (2.03 mean number of sites per visit). The three most common sites were at the insertions of the Achilles tendons and plantar fascia on the calcaneus, and the lateral epicondyles (24.2%, 20.8% and 17.2%, respectively).

More active disease (higher actively inflamed joint count, tenosynovitis and dactylitis), more pain and less clinical damage were associated with enthesitis. [[{"type":"media","view_mode":"media_crop","fid":"56016","attributes":{"alt":"(Plantar fascia ©MedicalArtInc/Shutterstock.com)","class":"media-image media-image-right","id":"media_crop_1234760427756","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"7031","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"font-size: 13.008px; float: right;","title":"(Plantar fascia ©MedicalArtInc/Shutterstock.com)","typeof":"foaf:Image"}}]]

In this study, radiographs were taken every two years. The increased use of ultrasound and magnetic resonance imaging over time has helped researchers detect and better understand enthesitis. Other imaging-based studies have shown that preclinical enthesitis exists in patients with the skin disease psoriasis. 

Recommended Next Steps

Knowledge gained from this study may help identify risk factors for enthesitis in patients living with inflammatory arthritis.

 

Disclosures:

This research was funded in part by the Krembil Foundation in Canada.

 

References:

Ari Polachek, Suzanne Li, Vinod Chandran, et al. “Clinical enthesitis in a prospective longitudinal psoriatic arthritis cohort: Incidence, prevalence, characteristics and outcome,” Arthritis Care & Research. Published online Dec. 20, 2016. DOI:  10.1002/acr.23174.