title: Epidemiology and sociodemographics of systemic lupus erythematosus and lupus nephritis among US adults with Medicaid coverage, 2000-2004.
abstract: OBJECTIVE
  Systemic lupus erythematosus (SLE) and lupus nephritis (LN) disproportionately affect individuals who are members of racial/ethnic minority groups and individuals of lower socioeconomic status (SES). This study was undertaken to investigate the epidemiology and sociodemographics of SLE and LN in the low-income US Medicaid population.
  
  
  METHODS
  We utilized Medicaid Analytic eXtract data, with billing claims from 47 states and Washington, DC, for 23.9 million individuals ages 18-65 years who were enrolled in Medicaid for >3 months in 2000-2004. Individuals with SLE (≥3 visits >30 days apart with an International Classification of Diseases, Ninth Revision [ICD-9] code of 710.0) and with LN (≥2 visits with an ICD-9 code for glomerulonephritis, proteinuria, or renal failure) were identified. We calculated SLE and LN prevalence and incidence, stratified by sociodemographic category, and adjusted for number of American College of Rheumatology (ACR) member rheumatologists in the state and SES using a validated composite of US Census variables.
  
  
  RESULTS
  We identified 34,339 individuals with SLE (prevalence 143.7 per 100,000) and 7,388 (21.5%) with LN (prevalence 30.9 per 100,000). SLE prevalence was 6 times higher among women, nearly double in African American compared to white women, and highest in the US South. LN prevalence was higher among all racial/ethnic minority groups compared to whites. The areas with lowest SES had the highest prevalence; areas with the fewest ACR rheumatologists had the lowest prevalence. SLE incidence was 23.2 per 100,000 person-years and LN incidence was 6.9 per 100,000 person-years, with similar sociodemographic trends.
  
  
  CONCLUSIONS
  In this nationwide Medicaid population, there was sociodemographic variation in SLE and LN prevalence and incidence. Understanding the increased burden of SLE and its complications in this low-income population has implications for resource allocation and access to subspecialty care.
authors.affiliation: Brigham and Women's Hospital, Boston, Massachusetts 02115, USA. chfeldman@partners.org
authors.forename: Candace H
authors.initials: CH
authors.lastname: Feldman
authors.forename: Linda T
authors.initials: LT
authors.lastname: Hiraki
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Michael A
authors.initials: MA
authors.lastname: Fischer
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Solomon
authors.forename: Graciela S
authors.initials: GS
authors.lastname: Alarcón
authors.forename: Wolfgang C
authors.initials: WC
authors.lastname: Winkelmayer
authors.forename: Karen H
authors.initials: KH
authors.lastname: Costenbader
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D017677:Age Distribution; D000368:Aged; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007198:Indians, North American / Q000706:statistics & numerical data; D008180:Lupus Erythematosus, Systemic / Q000208:ethnology*; D008181:Lupus Nephritis / Q000208:ethnology*; D008297:Male; D008484:Medicaid / Q000706:statistics & numerical data*; D008875:Middle Aged; D008913:Minority Groups / Q000706:statistics & numerical data*; D015995:Prevalence; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult