Patients with psoriatic arthritis (PsA) who were older, more active, and taking biologic medications had greater levels of inflammatory enthesitis on ultrasound, according to study results published in The Journal of Rheumatology. Compared with healthy control patients, patients with PsA demonstrated more structural damage but similar entheseal inflammatory changes.
While enthesitis is common in PsA, clinical symptom interpretation can be difficult. Better diagnostic and imaging techniques are required to accurately differentiate inflammatory from other forms of enthesopathy. Investigators sought to examine associations between ultrasound findings and PsA clinical characteristics, in addition to comparing patients and healthy controls.
Between May and August 2016, consecutive outpatients with PsA were enrolled in a cross-sectional study, regardless of age, disease activity, or complaints; healthy controls age 35 to 60 were also recruited. A structured interview gathered data on disease activity, symptoms, and physical activity, and medication use was derived from medical records. Physical exams were performed, followed by blinded ultrasound imaging.
Researchers analyzed 84 patients (mean age, 55; 54% men; median disease duration, 8 years) with mostly mild disease and 25 healthy controls (mean age, 47; 48% men). A modified form of the Madrid Sonographic Enthesitis Index (modified MASEI) was used to score entheseal inflammatory and structural changes in all participants. Linear regression analysis evaluated associations between patient clinical and ultrasound findings, and Wilcoxon rank tests were used to compare ultrasound results of patients and controls.
A higher inflammatory modified MASEI score was weakly associated with older age (β =0.07; 95% CI, 0-0.13; P =.050) and current biologic agent use (β =1.56; 95% CI, 0.16-2.95; P =.029), while lower inflammatory modified MASEI scores were significantly associated with avoidance of physical activity (β = −1.71; 95% CI, −3.1 to −0.32; P =.017). A higher structural modified MASEI score was significantly correlated with older age (β =0.03; 95% CI, 0.01-0.05; P =.001).
Researchers also compared ultrasound findings of 50 patients age 35 to 60 with 25 controls and found that while inflammatory modified MASEI scores were comparable (median scores, 5 vs 3.5; P =.16), the patient group demonstrated significantly higher structural modified MASEI scores (median scores, 6 vs 3; P =.005).
Study limitations included a cross-sectional design, possible information bias, use of self-reports, difficulty assessing physical activity, and testing of multiple factors of influence in an exploratory format.
“The larger extent in which structural changes were present in PsA patients in our study suggests that patients have been subject to more chronic inflammation of the entheses than healthy volunteers of similar age,” noted the investigators, adding, “Comparable inflammatory scores of healthy volunteers and PsA patients suggest that ultrasound evaluation of the enthesis is of limited value in screening for inflammation.” They recommended that future research involve longitudinal studies to confirm and expand on their findings.
Wervers K, Herrings I, Luime JJ, et al. Association of physical activity and medication with enthesitis on ultrasound in psoriatic arthritis. J Rheumatol. doi:10.3899/jrheum.180782