Undocumented status: Measurement and definition in public health research

BACKGROUND  Undocumented immigrants in the United States face a complex web of legal, political, and economic factors that shape their health environments. Data on this population is critical; however, given their vulnerability measurement of undocumented status must be thoughtful.  Research must be based on a clear methodology for measuring undocumented status in community populations. Yet, no systematic review has examined how undocumented status is measured and defined in health research.  Improved understanding of the health of undocumented individuals allows health professionals to provide health care and promote healthy environments. Therefore, this study reviews how public health research defines and measures undocumented status through a systematic review of recent studies. METHODS  For our systematic review, we compiled recent public health articles on undocumented immigrants and coded each on its classifications of undocumented status. RESULTS  Four measurement methodologies were identified: explicit, where status was asked directly; deductive, where status was determined by process of elimination; and proxy, where status was estimated via respondent characteristics.  Assumptions underlying the definitions of undocumented include: status is legally and socially determined; status is a fixed social position; and status results in mechanisms affecting health.  CONCLUSION  Public health interventions and policies require a better understanding of the factors that affect the health of undocumented immigrants. This study identifies approaches that are currently being used and that can adapted to future public health research to expand the base of knowledge on this vulnerable population.