Background/Purpose: Enthesitis is an important manifestation of psoriatic arthritis (PsA). We aimed to compare the frequency of ultrasonographic (US) entheseal abnormalities between patients with PsA, psoriasis without arthritis (PsC) and healthy controls and to assess the correlation between disease-related variables and the extent of US enthesitis.

Methods: PsA and PsC patients who were part of two large prospective cohorts were recruited. PsC patients were assessed by a rheumatologist to exclude inflammatory arthritis. Healthy controls were recruited from hospital personnel. Ultrasound examinations were performed using a MyLab 70 XVG device equipped with 6–18 MHz linear transducer and Doppler frequency of 7.1-14.3 MHz. The following entheseal insertion sites were examined: patella (at insertions of the quadriceps and patellar tendons), tibial tuberosity, Achilles tendon and plantar fascia insertions to the calcaneous and triceps tendon insertion to the olecranon. Two scoring systems for US enthesitis (MAdrid Sonographic Enthesitis Index (MASEI) and Glasgow Enthesitis Scoring System (GUESS)) were used to generate scores that reflect the severity of entheseal abnormalities in each patient. Analysis of variance was used to compare GUESS and MASEI scores across the groups. Chi square test was used to compare the frequencies of entheseal abnormalities between the groups. The correlation between disease-related variables and enthesitis scores was assessed by Pearson correlation coefficients (r).

Results: A total of 59 PsA patients, 79 PsC patients and 60 healthy controls were assessed. The frequency of US entheseal abnormalities was high with 98.3% of PsA patients, 97.5% of PsC patients and 86.7% of healthy controls having at least one abnormality. However, the extent of US abnormalities showed a trend with the highest score found in PsA patients followed by PsC patients and lowest in the controls (GUESS 8.9±4.6, 5.6±3.5 and 4.4±3.9, respectively p<0.001, MASEI 18.5±13, 9.9±7.4 and 7.7±9.2, respectively p<0.001). GUESS and MASEI correlated significantly with age (p<0.001 for each score) and Body Mass Index (p<0.001 for each score) and after adjusting for these variables the difference in enthesitis scores across the groups were not significant. The frequency of individuals who had tendon hypoechogenicity (p<0.001) and thickening (p<0.001), bony erosions (p<0.001) and positive Doppler signal (p=0.04) at the entheses was highest in PsA patients compared to both PsC and healthy control. No difference was observed in the frequency of individuals with calcifications or bursitis at the entheses. Among patients with PsA, C-reactive protein (CRP) and modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) correlated with GUESS (r=0.45, p=0.002 and r=0.44, p=0.004, respectively) and with MASEI (r=0.51, p=0.0007 and r=0.56, p=0.0005, respectively).

Conclusion: The prevalence of US entheseal abnormalities is high even among healthy individuals. However, their severity is highest in PsA patients followed by PsC and is lowest in healthy controls. Such abnormalities are associated with age, obesity, CRP and in PsA with the severity of radiographic axial damage.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ultrasonographic-entheseal-abnormalities-among-patients-with-psoriatic-arthritis-psoriasis-alone-and-healthy-individuals-and-their-correlation-with-disease-related-variables/