Background Enthesitis is one of the potential extra-axial manifestations found in patients with spondyloarthritis (SpA). Enthesitis can be quantified using the MASES (Maastrich Ankylosing Spondylitis Enthesitis Score), consisting 13 pre-defined entheses assessed for tenderness. There are few data on the MASES outside of RCTs. To better understand the impact of enthesitis real live data are needed.
Objectives To analyse (i) cross-sectionally the correlation of enthesitis with clinical, personal outcome parameters and (ii) longitudinally the development of enthesitis under treatment in patients with axial spondyloarthritis.
Methods We included all patients from the Swiss national registry SCQM with axial spondyloarthritis and valid MASES at baseline. Patients were analysed for demographics at baseline, physical assessments (BASMI, BASFI, BASDAI) and patient centered outcomes (SF36). Continuous variables were compared using a Student's T-test, categorical variables with χ2 test. Spearman's Rho or linear regression were employed for correlational analyses. Patients were analysed for changes in MASES depending on the initial MASES scores and the therapeutic strategy employed: synthetical DMARDs vs. TNF antagonists.
Results 3241 patients were included into the study. 45.9% of the patient had no entheseal affection at baseline (MASES =0). 59.7% of the patients were HLA B27 pos. and 60.5% of the patients were suffering from axial disease as defined by the New York criteria. The frequency of patients achieving higher MASES scores decreased linearly (R2: 0.4823, p=0.0058). Moderate associations were found for BASDAI, BASFI, patient's and physician's assessments of disease activity patients assessment of pain, the SF 36 mental and physical component score (Spearman's Rho: 0.403, 0.328, 0.326, 0.381, 0.352, -0.215, -0.326, respectively).
The average response of MASES after 1 year increases linearly with higher average MASES scores (slope -0.41, R2 =0.78). Patient with a MASES of zero at baseline developed an increase of MASES during follow up (average after 12 month: 0.48). Patients treated with TNF antagonists or DMARDs had a mean change of -1.15 and -1.03 at 12 months, respectively (p=0.967).
Conclusions Almost half of the axial SpA patients suffered from entheseal involvement. Half of the patients with a MASES of zero at baseline developed an entheseal involvement during follow up. Higher MASES scores correlate with parameters indicative of disease activity and patient related outcomes. In those with MASES over 1 the score decreased under treatment during follow up. However, changes of MASES under TNF antagonist or DMARD treatment did not differ in our cohort. In conclusion, a focussed analysis on enthesitis and its therapeutic strategy in SpA is needed.
Disclosure of Interest None declared