Correlation of enthesitis indices with disease activity and function in axial and peripheral spondyloarthritis: a cross-sectional study comparing MASES, SPARCC and LEI.

Background: The presence of enthesitis is associated with higher disease activity, more disability and incapacity to work and a poorer quality of life in spondyloarthritis (SpA). There is currently no consensus on which clinical score should be used to assess enthesitis in SpA. The objective of the present work was to compare the correlation of three enthesitis indices (MASES, SPARCC and LEI) with measures of disease activity and function in a heterogeneous population of patients with axial and peripheral SpA.

Methods: A cross-sectional study was conducted in three Brazilian public university hospitals; patients fulfilling ASAS classification criteria for peripheral or axial SpA were recruited and measures of disease activity and function were collected and correlated to three enthesitis indices: MASES, SPARCC and LEI using Spearman's Correlation index. ROC curves were used to determine if the the enthesitis indices were useful to discriminate patients with active disease from those with inactive disease.

Results: Two hundred four patients were included, 71.1% (N = 145) fulfilled ASAS criteria for axial SpA and 28.9% (N = 59) for peripheral SpA. In axial SpA, MASES performed better than LEI (p = 0.018) and equal to SPARCC (p = 0.212) regarding correlation with disease activity (BASDAI) and function (BASFI). In peripheral SpA, only MASES had a weak but statistical significant correlation with DAS28-ESR (r 0.310 p = 0.05) and MASES had better correlation with functional measures (HAQ) than SPARCC (p = 0.034).

Conclusion: In this sample composed of SpA patients with high coexistence of axial and peripheral features, MASES showed statistical significant correlation with measures of disease activity and function in both axial and peripheral SpA.