Clinical,immunogenetic and outcome features of Hispanic systemic lupus erythematosus patients of different ethnic ancestry

Abstract

The aim of this study was to compareand contrastthe clinical, immunogeneticand outcome featuresof two subgroups of Hispanic patients with systemic lupus erythematosus (SLE), one from Northern Spain (Spaniards) and one of from the USA (Hispano-Americans: Hispanics primarily of Mexican ancestry (Amerindian and Spaniard backgrounds). Patients with SLE as per the American College of Rheumatology classification criteria, from two University-affiliated Hospitals (Universidad de Cantabria) and disease of five or less years in duration (n 28) and with four years of follow up constituted the Spaniard subgroup. Fifty-two patients of Hispano-American ancestry from the LUMINA (Lupus in Minority populations: Nature versus Nurture) cohort constituted the Hispano-American subgroup. Patients were studied using a similar protocol. In short, sociodemographic, clinical, immunological, immunogenetic and psychosocial and behavioral features were obtained at enrollmentinto the study(baselinevisit) and yearly thereafter.The relationshipbetweenthesevariables and disease activity at baseline and over time, as measured by the systemic lupus activity measure (SLAM) and disease damage, as measured by the SLICC (Systemic Lupus InternationalCollaborating Clinics) Damage Index(SDI) were determined.Variablesfound to be significant at P 0.10 were then entered into multivariablelinear regression models with disease activity at baselineand over time, and damage as the outcome measures. Patients of Hispano-American and Spaniard ethnicity had comparablesociodemographicfeaturesexceptforhome density, which was higheramong theHispano-Americans.HLA-DRB1*08 was associatedwith SLE among the Hispano-Americansbutnotamong the Spaniards.Hispano-Americanpatientshad more severediseaseas manifestedby more frequentclinical manifestations(renal and neurological), higher SLAM scores at baselineand over time and higher SDI scoresat the year4 visit(thatdespitethefactthat Hispano-Americanpatientshad overallshorterdisease durationthan the Spaniard patients). Hispano-Americanethnicity, youngerage at disease onset and the number of ACR criteria at baseline and over time were consistently associated with disease activity, whereas increasedhome density and the absence of HLA-DRB1*0301 were significant predictors only over time. Disease damagewas associatedwith diseaseactivityover time, the number of ACR criteriaat baseline, increasedhomedensityandthe presenceof HLA-DRB1*08. This is thefirst longitudinalstudy of SLE in two different Hispanic subgroups. Hispanics with a strong Amerindian background have a more seriousdisease than that observedin Spaniards.Genetic and socio-economicdifferencesbetween these two Hispanic subgroups probably account for these findings