The identification of association between ultrasonographic enthesitis and the ASAS Health Index in patients with axial spondyloarthritis.

This study aimed to evaluate association between the entheseal abnormalities in ultrasound and the Assessment of Spondyloarthritis International Society Health Index (ASAS HI) in patients with axial spondyloarthritis (axSpA). Seventy-four patients with axSpA were enrolled in this study. Ultrasonographic evaluation of entheses was performed by a blinded rheumatologist with the Madrid Sonographic Enthesitis Index (MASEI). The MASEI total score and the MASEI sub-scores (e.g., structural damage and activity scores) were calculated. The ASAS HI and the other SpA tools (e.g., Bath Ankylosing Spondylitis Disease Index, the Ankylosing Spondylitis Disease Activity Score) were used to evaluate patients' health and disease activity. Correlation and multivariate linear regression analyses were performed to assess the relationship between the MASEI and the ASAS HI. The mean score of the ASAS HI was 7.7 ± 4.6. The MASEI total score was calculated as 8.4 ± 6.8, while the mean MASEI-activity was 4.7 ± 3.6 and the mean MASEI-structural damage was 3.8 ± 4.5. There was no correlation between ASAS HI and MASEI total scores (r = 0.11, p = 0.34). However, the ASAS HI had a positive correlation with the MASEI-activity (r = 0.49, p < 0.001) and had a low negative correlation with the MASEI-structural damage (r = - 0.29, p < 0.05). In the linear regression model, the MASEI-activity and MASEI-structural damage were significantly related to the ASAS HI (β = 0.72 and - 0.58, respectively; R 2  = 0.53 p < 0.001). This study reported that the ASAS HI score was more negatively affected by active entheseal lesions rather than structural lesions. We suggest adding the entheses evaluation with ultrasonography to other tools for monitoring the health status of patients with axSpA.