Psoriatic arthritis (PsA) is an inflammatory rheumatic disease with diverse manifestations, including axial skeleton disorders, nail and skin changes, peripheral joint inflammation, enthesitis, and/or dactylitis. Approximately 35%-50% of patients with PsA may have enthesitis—inflammation of the tendons, ligaments, or joint capsule fiber insertion into the bone—that can result in pain at the back of the heel, sole of the foot, around the elbows, or in other areas. Previous research indicates that patients with PsA with enthesitis have a greater disease burden than those without enthesitis; however, it is unknown whether the impact of enthesitis differs by the location of the body affected, which may help inform physicians about important areas of focus for clinical evaluations.
Comparing Disease Activity & QOL
For an exploratory analysis published in The Journal of Rheumatology, my colleagues and I sought to compare disease activity and quality of life (QOL) between patients with PsA who have enthesitis at different locations (upper sites only, lower sites only, or both upper and lower sites) and those without enthesitis, and to assess the impact of enthesitis by site.
This cross-sectional observational study included all adult patients with PsA enrolled in the Corrona PsA/Spondyloarthritis (SpA) Registry between March 2013 and March 2018. Enthesitis at enrollment was assessed via the Spondyloarthritis Research Consortium of Canada Enthesitis Index (SPARCC) and classified by affected sites (upper, lower, or both). Disease activity (eg, Clinical Disease Activity Index [CDAI], clinical Disease Activity Index for PsA [cDAPSA]), patient-reported outcomes (PROs; eg, patient-reported pain and fatigue), and work productivity were compared between those with and without enthesitis. The association of enthesitis with disease activity and PRO measures versus no enthesitis was modeled using multivariable-adjusted linear or logistic regression.
A total of 2,003 patients with PsA were included in the analyses, of whom 391 (19.5%) had a positive SPARCC score consistent with enthesitis at enrollment. Of the 391 patients with enthesitis, 80 (20.5%) had enthesitis in upper sites only, 137 (35.0%) in lower sites only, and 174 (44.5%) in both upper and lower sites. All enthesitis groups had a greater prevalence of fibromyalgia versus the group with no enthesitis. Patients with enthesitis in upper sites only and in both upper and lower sites also had a greater prevalence of nail psoriasis, and those with enthesitis in lower sites only had a greater prevalence of depression compared with those without enthesitis (all P<0.001)
Negative Impact Regardless of Site
Regardless of location of enthesitis sites, patients with enthesitis had worse disease activity, QOL, work productivity, and activity impairment than patients without enthesitis. Patients with enthesitis in both upper and lower sites tended to have worse disease activity (eg, minimum disease activity, CDAI, tender joint count, DAPSA, and cDAPSA) and QOL (eg, EQ VAS) than those with enthesitis in upper sites only or in lower sites only. Patients with enthesitis in lower sites only tended to have worse PROs (eg, pain and fatigue) and greater work productivity and activity impairment than those with enthesitis in upper sites only.
In adjusted models, presence of enthesitis at any site was significantly associated with worse disease activity compared with no enthesitis. Enthesitis in lower or both upper and lower sites was associated with higher pain and fatigue scores and greater work impairment versus no enthesitis. For several outcomes, there was a trend toward increasing impact by location of enthesitis sites (lowest to highest: upper sites only, lower sites only, both upper and lower sites) on disease activity (CDAI and cDAPSA), QOL (pain, fatigue, and Health Assessment Questionnaire Disability Index), and work productivity and activity impairment (Figure).
Our findings suggest that the presence of clinically defined enthesitis is associated with worse PsA disease severity, regardless of enthesitis location. In this real-world cohort, we observed that patients with enthesitis in lower or both upper and lower sites had worse pain, fatigue, and work impairment. Assessing enthesitis in both upper and lower sites may improve our understanding of the full scope of PsA disease activity.
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