What have we learned from a 10-year experience with the lumina (Lupus in Minorities; Nature vs. nurture) cohort? Where are we heading?

Abstract

Recently, there has been an awareness of the variable phenotypic expression of numerous disorders between individuals from different ethnicities, systemic lupus erythematosus (SLE) one of them. These disparities probably arise from the interaction between genetic and non-genetic (environmental, socioeconomic–demographic, cultural and behavioral) factors. To delineate the influence of these factors on SLE outcome, we established a multiethnic (Hispanic, African American and Caucasian) United States (US) early cohort (<5 years disease duration). Ten years later, interesting data have emerged from the LUMINA (Lupus in Minorities: Nature vs. nurture) cohort. For example, African Americans and Hispanics from Texas have a more severe disease than Caucasians and Hispanics from Puerto Rico. Lack of private insurance, acute SLE onset, expression of HLA-DRB1*01 (DR1) and C4A*3 alleles were associated with higher disease activity, whereas age, the number of American College of Rheumatology criteria met, disease activity, corticosteroid use and abnormal illness behaviors were consistent predictors of damage. In turn, damage and poverty were found to predict mortality. We now plan to apply new approaches (genetic admixture) to deconfound the complex interaction between genetic and non-genetic factors influencing SLE outcome. These data may have impact on the development of policies aimed at eliminating health disparities in the US.

Introduction

Over the last few decades there has been an increased recognition of the variations in the expression and clinical course of acute and chronic diseases in patients from different ethnic groups, whether they are studied in their country of birth or not. These phenotypic differences may be explained by biologic–genetic factors or socioeconomic–demographic and psychosocial–behavioral factors or by the interaction between factors from these different domains. We established in 1994 a cohort of patients with systemic lupus erythematosus (SLE) of Hispanic, African American and Caucasian ancestry, in order to understand the relationship between ethnicity and this autoimmune disease [1]. We called this cohort LUMINA, for LUpus in MInorities: NAture vs. nurture). At the present time, the LUMINA cohort is constituted by patients from three geographic areas and medical institutions: The University of Alabama at Birmingham, The University of Texas-Houston Health Science Center and The University of Puerto Rico Medical Sciences Campus. The last one was added in 2001 in order to diversify the LUMINA Hispanic patient group and make it more comparable to the US Hispanic population. As of October 2003, the cohort consists of 587 patients (110 Hispanics from Texas, 85 Hispanics from Puerto Rico, 215 African Americans and 177 Caucasians), with a mean follow-up time of 40 months (range 0–113 months). Seventy-one percent of LUMINA patients are prevalent and 29% are incident cases (less than 6 months of disease duration at enrollment into the cohort).

We will now briefly review some salient features of the cohort, what we have learned in terms of possible predictors of outcome and finally describe where we are heading as we start LUMINA's second decade of fruitful existence. Given that the Hispanics from Puerto Rico entered the cohort relatively recently, most of the analyses to be presented include only the Hispanic patients from Texas (primarily of Mexican ancestry).