Prevalence and Incidence of Systemic Lupus Erythematous Among Arab and Chaldean Americans in Southeast Michigan

BACKGROUND: The Michigan Lupus Surveillance and Epidemiology (MILES) Program developed a population-based Systemic Lupus Erythematous (SLE) registry for Southeast Michigan (Wayne and Washtenaw counties). Southeast Michigan has large Arab/Chaldean American populations; no studies have examined the SLE burden among these ethnic groups.

METHODS: Using the MILES registry, we calculated incidence and prevalence of SLE for Arab/Chaldean Americans (ACA) and compared these values to estimates for Non-Arab/Non-Chaldean Whites (NANCW) and Blacks residing in Southeast Michigan. The surveillance period included January 1, 2002 through December 31, 2005, and only SLE cases that met the American College of Rheumatology (ACR) definition (≥4 criteria) were counted. To identify Arab or Chaldean ethnicity, names of cases were matched to a database of Arab/Chaldean surnames and first names maintained by Wayne State University. We also linked SLE cases to birth certificate data and captured self-reported ancestry, race and country of birth. Based on name matches and supplemental birth certificate information, 54 cases were categorized as ACA. NANCW (n=886) and Blacks (n=1356) were identified based on race from the birth certificate or MILES registry. Population estimates for Wayne and Washtenaw counties were based on Census 2000 data with appropriate survey weights.

RESULTS: Overall incidence and prevalence of SLE per 100,000 ACA were 6.5 and 48.2, respectively. INCIDENCE: ACA females had a higher incidence of SLE than NANCW females (10.4 versus 6.4 per 100,000), but lower than Black females (14.0 per 100,000). Incidence among males was highest for ACA at 3.0 per 100,000 compared to 1.2 per 100,000 for NANCW males and 2.2 per 100,000 for Black males. PREVALENCE: Prevalence among females was lowest for ACA (90.4 per 100,000). NANCW females and Black females had prevalence estimates of 97.7 and 189.7 per 100,000, respectively. ACA males had a higher prevalence of SLE than NANCW males (11.5 versus 10.4 per 100,000), but lower than Black males (18.6 per 100,000).

CONCLUSIONS: Compared with NANCW and Blacks, ACA females had an intermediate incidence but lower prevalence of SLE. ACA males had a higher incidence but intermediate prevalence of SLE compared to NANCW and Black males. Difficulty in identifying individuals from these ethnic groups may lead to variations in ACA estimates. However, this study illustrates the importance of continued public health research to better understand the causes of morbidity among minority populations.