Association of Physical Activity and Medication with Enthesitis on Ultrasound in Psoriatic Arthritis

Objective. Enthesitis is a manifestation of psoriatic arthritis (PsA), but its symptoms are difficult to interpret clinically. We investigated the associations of ultrasonographic changes in entheses with clinical characteristics in patients with PsA, and compared enthesis changes of patients aged 35 to 60 years with healthy volunteers of that age. Methods. Consecutive patients with PsA participated in this cross-sectional study, irrespective of enthesitis complaints and age. We collected data about complaints, physical activity and activity avoidance, medication, and clinical enthesitis. Inflammatory and structural enthesis changes were scored with the modified MAdrid Sonographic Enthesitis Index (MASEI). Among all patients, associations between ultrasound (US) scores and clinical characteristics were investigated using linear regression. We compared US scores of healthy volunteers and patients with PsA aged 35-60 years using Wilcoxon rank-sum tests. Results. Eighty-four patients with PsA and 25 healthy volunteers participated. In patients with PsA, we found a small association between higher inflammatory-modified MASEI score and older age (beta 0.07, 95% CI 0-0.13) and current use of biologics (beta 1.56, 95% CI 0.16-2.95). Patients who reported avoiding activities had significantly lower inflammatory-modified MASEI scores (beta -1.71, 95% CI -3.1 to -0.32) than those who did not. The patients with PsA aged 35-60 years (n = 50) had similar inflammatory scores as healthy volunteers but higher structural scores (median 6 vs 2; p = 0.01). Conclusion. Within patients with PsA, avoiding physical activity, younger age, and not using biologics were associated with less enthesis inflammation. Patients with PsA and healthy volunteers aged 35 to 60 years displayed similar levels of inflammatory changes of the entheses, but patients had more structural damage.