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Ethnicity and disease severity in ankylosing spondylitis a cross-sectional analysis of three ethnic groups


The purpose of this study is to compare disease severity in ankylosing spondylitis (AS) in three ethnic groups. We assessed 925 AS patients (57 Blacks, 805 Whites, 63 Latinos) enrolled in the longitudinal Prospective Study of Outcomes in AS (PSOAS) for functional impairment, disease activity, and radiographic severity. Comparisons of clinical characteristics and HLA-B27 frequency for each group were performed, in two multivariable regression models, we compared the baseline Bath Ankylosing Spondylitis Radiographic Index (BASRI) and modified Stokes Ankylosing Spondylitis Spine Score (mSASSS) by ethnicity, adjusting for covariates. Blacks had greater functional impairment (Bath Ankylosing Spondylitis Functional Index) (median 62.5 vs. 27.8 in Whites and 38.1 in Latinos; p < 0.0001); higher disease activity (Bath Ankylosing Spondylitis Disease Activity Index), (median 5.9 vs. 3.5 in Whites and 4.5 in Latinos; p < 0.0001), erythrocyte sedimentation rate (median 27.0 in Blacks vs. 10.0 in Whites and 17.0; p < 0.0001), and C-reactive protein levels (median 1.2 vs. 0.4 mg/dL in Whites and 0.9 in Latinos; p < 0.0001). Baseline BASRI and mSASSS were higher in Blacks (mean 9.5 and median 38.2, respectively) compared to Whites (7.3 and 6.4) and Latinos (7.3 and 8.1), (p = 0.004, 0.007), respectively, more significant as disease duration increased. HLA-B27 occurred in 62.5% of Blacks, 85.3% of Whites, and 86.7% of Latinos (p < 0.0001). On multivariable analysis, higher BASRI and mSASSS were associated with Black ethnicity, after adjusting for disease duration and gender as well as TNF inhibitor (TNFi) usage, smoking status, or education level. Blacks with AS have more severe disease compared to either Whites or Latinos.

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Supported by grants from the US Department of Health and Human Services, National Institutes of Health (NIH), and National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), P01-052915-06. We also acknowledge the support provided by the Biostatistics/Epidemiology/Research Design (BERD) component of the Center for Clinical and Translational Sciences (CCTS) for this project. CCTS is mainly funded by the NIH Centers for Translational Science Award (UL1TR000371) by the National Center for Advancing Translational Sciences (NCATS). Also, we acknowledge that management of data for this study was done using REDCap which was partly supported by a grant UL1 TR000445 from NCATS/NIH, awarded to Vanderbilt University. Dr. Michael Ward is supported by the Intramural Research Program, NIAMS, and NIH. Dr. Lianne S. Gensler is supported by the Rosalind Russell/Ephraim P. Engleman Rheumatology Research Center, San Francisco, CA. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or the NCATS. The investigators also acknowledge the extraordinary efforts of Vera Wirawan, Cheryl Kallmann, Lori Guthrie, Erin Shrok, Grace Yoon, and Stephanie Morgan, as well as the laboratory assistance of Rui Jin, MD.

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Correspondence to John D. Reveille.

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Jamalyaria, F., Ward, M.M., Assassi, S. et al. Ethnicity and disease severity in ankylosing spondylitis a cross-sectional analysis of three ethnic groups. Clin Rheumatol 36, 2359–2364 (2017).

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  • Ankylosing spondylitis
  • Blacks
  • Disease severity
  • HLA-B27
  • Latinos