The Assessment of Spondyloarthritis International Society (ASAS) health index (HI) was well-correlated with known disease parameters in patients with ankylosing spondylitis (AS) and nonradiographic axial spondyloarthritis (nr-axSpA) per study data published in the Journal of Clinical Medicine. Predictors of ASAS HI included spinal structural damage, high nonsteroidal anti-inflammatory drug (NSAID) intake, alcohol consumption, and economic status.

Investigators performed a cross-sectional study using data from the Catholic Axial Spondyloarthritis Cohort (CASCO), a prospective cohort of patients with axSpA recruited from Seoul Saint Mary’s Hospital in Seoul, South Korea. Per CASCO protocol, patients provided demographic, laboratory, and radiographic data at enrollment. Extracted laboratory values included erythrocyte sedimentation rate, C-reactive protein, and human leukocyte antigen.

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Lateral views of the cervical and lumbar spine were taken to calculate the modified stoke ankylosing spondylitis spinal score. Patients also completed paper questionnaires to determine patient-related outcomes, including ASAS HI. Socioeconomic status was assessed with regard to salary, education level, and marital status; NSAID intake was determined using patient medical records. Linear regression analysis was performed to identify factors associated with ASAS HI in the overall axSpA population and in each axSpA subgroup.

A total of 357 patients with axSpA were included in analysis: 261 with AS and 97 with nr-axSpA. Patients with AS were older and had greater disease duration compared with patients with nr-axSpA (both P <.001). Radiographic spinal structural damage was more severe in the AS group (P <.001). ASAS HI and environmental factors related to ASAS HI were higher in the AS group compared with the nr-axSpA group (P =.003 and P =.009, respectively). Patients most frequently endorsed ASAS HI items representing patient-perceived pain (No. 1; 57.7% in AS; 44.8% in nr-axSpA) and patient-perceived energy/drive (No. 5; 51.2% in AS; 44.8% in nr-axSpA).

ASAS HI correlated with other SpA-related parameters, including the Bath Ankylosing Spondylitis Disease Index, the Bath Ankylosing Spondylitis Functioning Index, and the Ankylosing Spondylitis Disease Activity Score (all P <.001). Per multivariable regression analysis, higher economic status and alcohol consumption were negatively associated with ASAS HI in the total axSpA group (P =.013 and P =.004, respectively). Higher NSAID intake and modified stoke ankylosing spondylitis spinal score had significant positive associations with ASAS HI (P =.003 and P =.006, respectively). Subgroup analyses yielded similar results, although for the nr-axSpA group, only alcohol consumption was negatively associated with ASAS HI (P =.023), rather than both alcohol consumption and economic status.

These data support the validity of the ASAS HI as a measure of overall health in patients with axSpA. ASAS HI may also be used to practically distinguish between AS and nr-axSpA and to assess actual discomfort in patients with axSpA. Factors associated with ASAS HI may also represent targets of intervention in clinical practice.

Reference

Min HK, Lee J, Ju JH, Park SH, Kwok SK. Predictors of Assessment of Spondyloarthritis International Society (ASAS) health index in axial spondyloarthritis and comparison of ASAS health index between ankylosing spondylitis and nonradiographic axial spondyloarthritis: data from the Catholic Axial Spondyloarthritis CoHort (CASCO). J Clin Med. 2019;8(4):467.