Figure 2.

Venn diagram depicting the overlap of cases identified by the 4 categories of case-finding sources used in the primary capture– recapture models. This diagram corresponds to unique prevalent cases classified as systemic lupus erythematosus (SLE) according to the American College of Rheumatology (ACR) definition. Capture– recapture modeling was performed using both 4-source and 5-source models; the models that used the 4 case-finding sources presented in this Venn diagram were determined to fit the data best and, thus, represent our primary capture–recapture modeling. The majority of cases in the registry (2,124 of 2,278 [93.2%]) meeting the ACR or rheumatologist definitions were ascertained from these 4 case-finding source categories. (The 2 case-finding sources that were not retained in the primary models were Medicaid and laboratory.) Based on the capture–recapture analysis of prevalent SLE cases meeting the ACR criteria, we estimated that an additional 7 prevalent SLE cases were in the source population (Wayne and Washtenaw Counties, Michigan, 2002–2004) but were not ascertained in the Registry. ESRD = end-stage renal disease (data from US Renal Data System).