The ASAS Health Index and Environmental Factors Item Set: validity and reliability of the Swedish translations in Swedish patients with ankylosing spondylitis.

OBJECTIVES: To translate the Assessment of SpondyloArthritis international Society (ASAS) Health Index (HI) Environmental Factors Item Set (EFIS) into Swedish and culturally adapt it for a Swedish context, and to assess the construct validity of the Swedish version of the ASAS HI and test-retest reliability in ASAS HI and EFIS in Swedish patients with ankylosing spondylitis (AS). METHOD: Translation and cross-cultural adaptation of the EFIS were carried out according to a forward-backward procedure consisting of five steps. The construct validity of the ASAS HI was tested using Spearman correlation with standard health outcomes for axial spondyloarthritis (axSpA). Reliability was analysed by internal consistency with the Cronbach's alpha coefficient for ASAS HI, and test-retest reliability with intraclass correlation coefficients (ICCs) for ASAS HI and kappa agreement for the individual items of EFIS. RESULTS: The translation of EFIS showed acceptable face and content validity. ASAS HI showed an acceptable internal consistency (Cronbach's alpha 0.79), and excellent test-retest reliability (ICC 0.87). Test-retest reliability for EFIS showed varied results, with kappa agreement for the individual items ranging from poor (-0.027) to good (0.80). CONCLUSIONS: The Swedish version of ASAS HI proved to be valid and reliable and is recommended for assessing the impact of AS on global functioning and health. A Swedish version of EFIS has been produced and uploaded on the ASAS website. The EFIS proved to have acceptable face and content validity, and may contribute to the contextual interpretation of the ASAS HI.

Factors associated with changes in volumetric bone mineral density and cortical area in men with ankylosing spondylitis: a 5-year prospective study using HRpQCT.

Patients with ankylosing spondylitis (AS) have impaired volumetric bone mineral density (vBMD) assessed with high-resolution peripheral computed tomography (HRpQCT). This first longitudinal HRpQCT study in AS shows that cortical and trabecular vBMD decreased at tibia and that signs of inflammation were associated with cortical bone loss at tibia and radius. INTRODUCTION: Patients with ankylosing spondylitis (AS) have reduced volumetric bone mineral density (vBMD) in the peripheral skeleton assessed with high-resolution peripheral quantitative computed tomography (HRpQCT). The aims were to investigate longitudinal changes in vBMD, cortical area, and microarchitecture and to assess factors associated with changes in vBMD and cortical area in men with AS. METHODS: HRpQCT of radius and tibia was performed in 54 men with AS at baseline and after 5 years. Univariate and multivariable linear regression analyses were used. RESULTS: At tibia, there were significant decreases exceeding least significant changes (LSC) in cortical and trabecular vBMD, mean (SD) percent change -1.0 (1.9) and -2.7 (5.0) respectively (p<0.001). In multivariable regression analyses, increase in disease activity measured by ASDAS_CRP from baseline to follow-up was associated with decreases in cortical vBMD (ß -0.86, 95% CI -1.31 to -0.41) and cortical area (ß -1.66, 95% CI -3.21 to -0.10) at tibia. At radius, no changes exceeded LSC. Nonetheless, increase in ASDAS_CRP was associated with decreases in cortical vBMD, and high time-averaged ESR was associated with decreases in cortical area. Treatment with TNF inhibitor ≥ 4 years during follow-up was associated with increases in cortical vBMD and cortical area at tibia, whereas exposure to bisphosphonates was associated with increases in cortical measurements at radius. No disease-related variables or treatments were associated with changes in trabecular vBMD. CONCLUSION: The findings in this first longitudinal HRpQCT study in patients with AS strengthen the importance of controlling disease activity to maintain bone density in the peripheral skeleton.