Browsing by Author "van der Heijde, D"
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- Both structural damage and inflammation of the spine contribute to impairment of spinal mobility in patients with ankylosing spondylitisPublication . Machado, P; Landewé, R; Braun, J; Hermann, KG; Baker, D; van der Heijde, DOBJECTIVE: To study the relationship between spinal mobility, radiographic damage of the spine and spinal inflammation as assessed by MRI in patients with ankylosing spondylitis (AS). METHODS: In this subanalysis of the Ankylosing Spondylitis Study for the Evaluation of Recombinant Infliximab Therapy cohort, 214 patients, representing an 80% random sample, were investigated. Only baseline data were used. MRI inflammation was assessed by the AS spinal MRI activity (ASspiMRI-a) score, structural damage by the modified Stoke AS Spine Score (mSASSS) and spinal mobility by the linear definition of the Bath Ankylosing Spondylitis Metrology Index (BASMI). Univariate correlations were calculated on baseline values using Spearman rank correlation. Independent associations between the variables of interest were investigated by multivariate linear regression analysis. Associations with clinical disease activity, C-reactive protein, disease duration, age, gender, body mass index and HLA-B27 status were also investigated. Subanalyses were performed according to disease duration. RESULTS: BASMI correlated moderately well with mSASSS (Spearman's rho=0.6) and weakly with ASspiMRI-a (rho=0.3). A best-fit model for BASMI included both mSASSS (regression coefficient (B)=0.865, p<0.001) and ASspiMRI-a (B=0.236, p=0.018). In patients with a disease duration < or = 3 years, B was greater for ASspiMRI-a than for mSASSS (0.595 vs 0.380), while in patients with a disease duration > 3 years B was greater for mSASSS than for ASspiMRI-a (0.924 vs 0.156). CONCLUSION: Spinal mobility impairment in AS is independently determined both by irreversible spinal damage and by reversible spinal inflammation. Spinal mobility impairment is more influenced by spinal inflammation in early disease, and by structural damage in later disease
- A stratified model for health outcomes in ankylosing spondylitisPublication . Machado, P; Landewé, R; Braun, J; Hermann, KG; Baraliakos, X; Baker, D; Hsu, B; van der Heijde, DOBJECTIVE: To investigate the relationships between several health outcomes in ankylosing spondylitis (AS). METHODS: Baseline pretreatment data from 214 patients with AS participating in the AS Study for the Evaluation of Recombinant Infliximab Therapy were analysed. Measures of health-related quality of life (HRQoL) and physical function were used as dependent variables in linear regression analysis. Associations between HRQoL (36-Item Short Form (SF-36)), physical function, clinical disease activity, spinal mobility, structural damage, MRI inflammation, disease duration, age, gender, body mass index and HLA-B27 were explored. Univariate associations were retested in multivariate models. The robustness of the models was evaluated by sensitivity analyses. RESULTS: The physical component of SF-36 was independently associated with measures of physical function and disease activity (adjusted R(2) (adjR(2))=0.39-0.40). The mental component of SF-36 was independently associated with physical function (adjR(2)=0.07). Physical function was independently associated with measures of spinal mobility and disease activity (adjR(2)=0.39-0.45). Spinal mobility was hierarchically shown to be an intermediate variable between structural damage and physical function, while physical function was shown to be intermediate between spinal mobility and the physical component of SF-36. CONCLUSION: According to the proposed stratified model for health outcomes in AS, HRQoL is determined by physical function and disease activity, physical function is determined by spinal mobility and disease activity, and spinal mobility is determined by structural damage and inflammation of the spine. As more is learnt about how to measure AS, knowledge about the disease improves and better decisions can be made on the assessment and treatment of this disease.