Unraveling the myth: Insuring the undocumented immigrants will not increase health care use

The undocumented immigrants are said to crowd emergency rooms and hospitals and are often blamed as the reason for the high level of health care expenditures. However, such arguments are generally presented in the absence of reliable data on utilization patterns of undocumented immigrants. To determine whether health care utilization patterns of undocumented immigrants differ from U.S. Citizens and legal residents, we examined service utilization of insured and uninsured undocumented to similarly insured documented residents.

We used data from 2005 California Health Interview Survey (CHIS). We predicted undocumented status of individuals who were not citizens or lacked permanent residency status in the U.S. using external data on immigration patterns of various nationalities. Insurance coverage was classified as private HMO, public HMO, private non-HMO, and public non-HMO. The health care utilization variables included number of doctor visits last year, an emergency room visit last year, a preventive visit last year, Pap test in the past three years, mammogram in the past two years, colorectal cancer screening in the past, and PSA screening in the past.

Utilization of care was assessed in Poisson regression for number of office visits and logistic regression for ER visits and preventive services. The regressions were adjusted for demographic and socioeconomic characteristics of the population that may modify their utilization patterns. All analyses were adjusted for the complex survey design of CHIS.

An estimated 4% of children and 8% of adults were undocumented immigrants. More undocumented immigrants children and adults were uninsured than U.S. born (30% vs. 5% and 53% vs. 11%, respectively). More undocumented immigrant children and adults were lived under 200% of the Federal Poverty Level than U.S. born individuals. Among uninsured children, adjusted service use did not differ significantly by documentation status. Among uninsured adults, undocumented immigrants had lower adjusted office visits, Pap test and mammograms rates but similar adjusted ER visits, colorectal, and PSA screening rates to documented residents. The adjusted service utilization rates of insured documented residents were statistically similar to that of insured documented residents.

The findings contradict the myth that undocumented immigrants use more health care than documented populations. In fact, undocumented immigrants were found to significantly underutilize important preventive services that could reduce future preventable morbidity and its related expenditures. Excluding the undocumented immigrants from proposals for universal health insurance coverage is unlikely to lead to long term improvements in overall health and reductions in health expenditures.