LAUSR

Background Evaluating psoriatic arthritis (PsA)-related enthesitis is diagnostically and therapeutically essential, but may be very complex because of the wide range of signs and symptoms that partly overlap or co-exist with the clinical features of fibromyalgia (FM) [1,2]. Objectives The primary aim was to compare the prevalence of clinical and ultrasonographic signs of enthesitis in patients with PsA, FM, or both. The secondary aim was to assess the impact of FM on disease activity and clinimetric scores. Methods This single-centre, observational cross-sectional study involved 101 consenting patients: 39 with PsA (CASPAR criteria), 23 with FM (2016 criteria), and 39 with both. Standard PsA and FM clinical, laboratory and clinimetric data were recorded. Disease activity in PsA and PsA-FM patients was assessed using BASDAI and ASDAS. The entheses were assessed using LEI and MASES score. All of the patients underwent B mode (grey scale) ultrasonography, the US findings were scored using the GUESS. Results The mean age of the patients was 53.6 years, SD ± 9.47. Females accounted for 64.1% of the PsA patients (disease duration 9.13 years, SD ± 5.9), 95.6% of FM patients (disease duration 5.09 years, SD ± 3.6), and 92.3% of the patients with PsA-FM (disease duration 7.9 years, SD ± 5.5). There were no between-group differences in the patients’ BMI. None of the FM subjects reported any personal or family history of psoriasis. The mean PASI was 2.3 ± 3.1 in the PsA group, and 1.2 ± 2.45 in the PsA-FM group. The median BASDAI was significantly higher in PsA-FM vs PsA group (7.7 [IQR 2.1] vs 5.0 [IQR 3.8]; p<0.001), as well the median ASDAS score ESR-assessed (3.69 [IQR 1.00] vs 2.82 [IQR 1.55]; p=0.004), or PCR- assessed (median 3.27 [IQR 1.07] vs 2.66 [IQR 1.26]; p = 0.006). Clinical evidence of enthesopathy was found in 43% of PsA, 51.3.8% of PsA-FM, and 50.8% of FM, while US entheseal abnormalities were detected in respectively 65%, 54.6% and 30%. The median MASES was significantly higher in FM or PsA-FM than in PsA group (p<0.001), no statistically significant difference between FM vs PsA-FM groups (6 [IQR 2] vs 7 [IQR 3]; p=0.737). The median LEI was significantly higher in FM or PsA-FM groups(p<0.001),with no statistically significant difference between these two groups(6 [IQR 2] vs 7 [IQR 3]; p=0.658). The median GUESS was significantly higher in PsA vs FM group (9 [IQR 7.5] vs 3 [IQR 2]; p<0.001), and in PsA-FM vs FM group (8 [IQR 4.5] vs 3 [IQR 2]; p<0.001). No statistically significant difference between PsA and PsA-FM group (9 [IQR 7.5] vs 8 [IQR 4.5]; p<0.112). No statistically significant Spearman correlation coefficient(rho) was found between GUESS and MASES/LEI in any of the groups. There was a correlation between GUESS scores and disease duration in PsA (rho=0.37; p=0.019, 95% CI 0.10-0.61) or PsA-FM (rho=0.38; p=0.016, 95% CI 0.10-0.61), but not in the FM group, and GUESS scores correlated with BMI (rho=0.2; p=0.05, 95% CI 0.00-0.37) and dyslipidemia (rho=0.34; p=0.006, 95% CI 0.11-0.58) in all groups. Conclusion The use of a clinical examination and clinimetric scores alone may overestimate active enthesitis in FM patients. As US was more frequently positive in patients with PsA and PsA-FM than in those with FM, it may be useful in differentiating pain due to enthesitis from entheseal pain due to FM. References [1] Marchesoni A, et al. The problem in differentiation between psoriatic-related polyenthesitis and fibromyalgia. Rheumatology. 2018;57:32-40 [2] McGonagle D. Enthesitis: an autoinflammatory lesion linking nail and joint involvement in psoriatic disease.J Eur Acad Dermatol Venereol2009;23:9–13 Disclosure of Interests Alessia Fiorenza : None declared, Gianluca Bonitta Consultant for: Sanofi, Elisabetta Gerratana : None declared, Francesca Marino: None declared, Pietro Muto: None declared, Donatella Sangari: None declared, Piercarlo Sarzi-Puttini Speakers bureau: Novartis, Fausto Salaffi Grant/research support from: Abbvie, Roche, Novartis, BMS, Pfizer, Sanofi, Speakers bureau: Abbvie, Roche, Novartis, Pfizer, Sanofi, BMS, Fabiola Atzeni: None declared