Background/Purpose: Enthesitis is an important aspect of disease in PsA and its clinical assessment has problems in terms of sensitivity and overlap with alternative co-morbid conditions. Imaging has emerged as the preferred option to assess enthesitis and research has demonstrated that those with persistent active US entheseal disease are at risk of progressive articular damage. There is limited data to help clinicians select the most appropriate biologic therapy for PsA patients. We wanted to assess the response on active US confirmed enthesitis to different forms of biologic therapy to study its utility in making more informed decisions and correlate clinical and imaging data.

Methods: The MAdrid Sonographic Enthesitis Index (MASEI) score assesses both chronic and active entheseal disease and is validated for use in SpA. The MASEI score was modified to count only the active elementary lesions (ActiveMASEI) which include hypoechogenicity, bursitis, tendon thickness and active power doppler signal at 12 entheses sites. This was a prospective observational study and to be included patients had to be aged ≥ 18 years, fulfil the classification criteria for PSA (CASPAR) and due to commence on their first biologic therapy. The trained sonographer was blinded to all clinical findings and treatment choice prior to scanning. All patients were rescanned at 16 weeks of treatment as per their first review by the same investigator blinded to treatment and clinical outcomes.

Results: In total 80 patients were enrolled. All patients received the licensed dosing with 24 patients commenced on secukinumab (150mg n =18, 300mg n = 6) and 56 on TNFi (Adalimumab n = 50, certolizumab pegol n =4 and etanercept n = 2). 75 patients completed the study (Secukinumab n = 23 and TNFi n= 52). Baseline characteristics are as per Table 1 and were broadly similar for either class of biologic apart from the baseline DLQI (Skin questionnaire) score. The average age was 45.29 yrs (12.74) and 42 (52.5%) participants were female.

The mean ActiveMASEI score reduction was 4.37 (5.31) with TNFi compared with 2.22 (3.01) for secukinumab which was significant (-2.148(-4.080, -0.216) p = 0.030). The Spondyloarthritis Research Consortium of Canada Enthesitis Index (SPARCC) correlated with the baseline ActiveMASEI score as per Spearman’s Rank (rs = 0.23 p = 0.04) and a change in SPARCC significantly correlated with a change in ActiveMASEI (rs =0.30 p = 0.01). This was not seen with the Leeds Enthesitis Index (LEI) score at baseline or with change (rs= 0.07 p = 0.51 and rs =0.14 p = 0.23 respectively). Clinical outcomes are noted in table 2 and apart from a significant reduction in regards to the PASI and DLQI score with Secukinumab versus TNFi ( 3.44 (3.50) vs 1.03 (2.30) p = 0.001 and 5.57 (7.52) vs 1.35 (4.18) p = 0.005 respectively) similar findings were seen for both classes of biologic therapy.

Conclusion: In this study we have compared the effect on active US confirmed enthesitis between different forms of biologic therapy for PsA. We have demonstrated superiority of TNFi versus secukinumab in regards to active entheseal disease. The SPARCC score correlated with baseline active entheseal US disease and with change in response to treatment highlighting it ability to capture active entheseal disease.

Table 1: Baseline characteristics as per class of biologic treatment. All variables with SD unless stated and assessed per group by an Independent T test apart from sex which was by Fisher’s Exact Test

Table 2 Change in clinical outcomes from baseline after 16 weeks of treatment. Outcomes assessed with an independent t test apart from PsARC and MDA criteria which used a Chi square test

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/effects-of-tnf-%ce%b1-versus-secukinumab-on-active-ultrasound-confirmed-enthesitis-in-psoriatic-arthritis/