Limited available comparative evidence does not support one monotherapy over another for adults with rheumatoid arthritis. Although combination therapy is more effective for patients whose monotherapy fails, the evidence is insufficient to draw firm conclusions about whether one combination or treatment strategy is better than another or is the best treatment for early rheumatoid arthritis.
Objective. To determine whether shared epitope (SE)-containing HLA-DRB1 alleles are associated with rheumatoid arthritis (RA) in African Americans and whether their presence is associated with higher degrees of global (genome-wide) genetic admixture from the European population.Methods. In this multicenter cohort study, African Americans with early RA and matched control subjects were analyzed. In addition to measurement of serum anti-cyclic citrullinated peptide (anti-CCP) antibodies and HLA-DRB1 genotyping, a panel of >1,200 ancestry-informative markers was analyzed in patients with RA and control subjects, to estimate the proportion of European ancestry.Results. The frequency of SE-containing HLA-DRB1 alleles was 25.2% in African American patients with RA versus 13.6% in control subjects (P ؍ 0.00005). Of 321 patients with RA, 42.1% had at least 1 SEcontaining allele, compared with 25.3% of 166 control subjects (P ؍ 0.0004). The mean estimated percent European ancestry was associated with SE-containing HLA-DRB1 alleles in African Americans, regardless of disease status (RA or control). As reported in RA patients of European ancestry, there was a significant association of the SE with the presence of the anti-CCP antibody: 86 (48.9%) of 176 patients with anti-CCP antibody-positive RA had at least 1 SE allele, compared with 36 (32.7%) of 110 patients with anti-CCP antibodynegative RA (P ؍ 0.01, by chi-square test).Conclusion. HLA-DRB1 alleles containing the SE are strongly associated with susceptibility to RA in African Americans. The absolute contribution is less than that reported in RA among populations of European ancestry, in which ϳ50-70% of patients have at least 1 SE allele. As in Europeans with RA, the SE association was strongest in the subset of African American patients with anti-CCP antibodies. The finding of a higher degree of European ancestry among African
Objective To examine the prevalence of vitamin D insufficiency and the associations of vitamin D concentration with disease status in African Americans with rheumatoid arthritis (RA). Methods Study participants (n = 266) were enrolled in the Consortium for the Longitudinal Evaluation of African Americans with Early RA (CLEAR) Registry. 25(OH)-D was measured on baseline plasma and associations of 25(OH)-D with disease status (baseline and at 3 years disease duration) were examined using univariate and multivariate regression. Results The prevalence of 25(OH)-D insufficiency (≤ 37.5 nmol/L or 15 ng/ml) was 50%, with the highest prevalence in winter. In unadjusted analyses, vitamin D concentrations were inversely associated with baseline pain (p = 0.04), swollen joints (p = 0.04), and Disease Activity Score (DAS-28, p = 0.05) but not with measures at 3 years disease duration. There were no multivariate associations of 25(OH)-D with any disease measures at baseline or at 3 years with the exception of a positive borderline association with rheumatoid factor positivity at enrollment (p = 0.05). Conclusions Vitamin D insufficiency is common in African Americans with recent-onset RA. Unadjusted associations of circulating vitamin D with baseline pain, swollen joints, and DAS-28 were explained by differences in season, age, and gender and were not significant in multivariate analyses. In contrast to reports of Northern Europeans with early inflammatory arthritis, there are not strong associations of 25(OH)-D concentration with symptoms or disease severity in African Americans with RA.
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