Objective: To ascertain whether there are any geographic clusters of systemic lupus erythematosus (SLE), and critically review 2 previous reports of these clusters.
Methods: A literature review of all epidemiologic surveys relevant to SLE published since 1966 was undertaken. This included a search of abstracts and reports, in addition to peer-reviewed publications.
Results: Two geographic clusters were identified in the literature. A report purporting that contaminated ground water in southwest Tucson, Arizona was associated with significantly increased symptoms of SLE was flawed since no patients were examined, discarded criteria were used, and incorrect definitions were employed by the nonrheumatologist authors. Another study, which identified a cluster in Nogales, Arizona, used generally valid methodology. However, the authors' conclusion that a 94/100,000 prevalence of SLE was evidence of an excessive increase in this 92% Hispanic/Native American community is not consistent with published surveys among Hispanic and Native American populations.
Conclusion: No valid claims of SLE geographic clusters have been published.