Background The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Ankylosing Spondylitis Disease Activity Index using C-reactive protein/Erythrocyte sedimentation rate base (ASDAS-CRP/ASDAS-ESR) are validated instruments for measuring disease activity in ankylosing spondylitis (AS) and other spondyloarthritis (SpA). The Bath Ankylosing Spondylitis Functional Index (BASFI) is validated to measure functional ability. Modified Schober test is used to assess mobility in these patients. Previous studies have found self-rated depressive symptoms to be associated with BASDAI and BASFI in AS (1). However, the effects of depression as diagnosed by a psychiatrist on various SpA instruments have not been performed.

Objectives To determine the effects of depression on various self-rated SpA instruments.

Methods One hundred and sixty one Chinese SpA patients who fulfilled the Assessment of Spondyloarthritis international Society (ASAS) classification criteria for axial SpA were recruited from the rheumatology clinic. Major depressive disorder was diagnosed by a psychiatrist using the Chinese-bilingual Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, fourth edition (CB-SCID). Socio-demographic parameters, Modified Schober’s test score, BASDAI, BASFI and ASDAS-CRP/ASDAS-ESR were compared using univariate analyses and variables with significant differences (p<0.1) were used as dependent variables in multivariate linear and logistic regression models using BASDAI, BASFI, ASDAS-CRP/ASDAS-ESR and depression as independent variables.

Results There were 113 (70.2%) males and the average age of all patients was 46.2 years. The mean duration of inflammatory back pain was 14.6 years. They were characterized by medium to high disease activity (mean BASDAI 3.94; mean ASDAS 1.57) and preserved functional status (mean BASFI 2.54). Seventeen (10.6%) of the patient were diagnosed as having major depressive disorder. In the multivariate linear regression model using BASDAI as the independent variable, a positive association with depression was found (B=1.33; p=0.01). However, no association was found with the same regression model using BASFI, ASDAS-CRP and ASDAS-ESR as independent variables (BASFI: B=0.14; p=0.82; ASDAS-CRP: B=0.31; p=0.09; ASDAS-ESR: B=0.15; p=0.47). When BASDAI was taken off from the dependent variable in the multivariate linear regression model using BASFI as the independent variable, depression was also found to be associated positively (B=1.65; p=0.02). In multivariate logistic regression model using depression as independent variables, BADAI was found to associate positively with depression (OR 1.47; p=0.04) while BASFI (OR 1.05; p=0.73) and modified Schober test’s (OR 0.77; p=0.24) were not.

Conclusions Depression is associated with higher BASDAI and BASFI. However, the association with BASFI is lost when adjusted against BASDAI. ASDAS-CRP/ASDAS-ESR have no association with depression and provide more objective assessment of the disease activity.

1. J Martindale, J Simth, CJ Sutton, et al. Disease and psychological status in ankylosing spondylitis. Rheumatology 2006; 45:1288-1293

Disclosure of Interest None Declared