Health Insurance and Mortality in US Adults

The United States stands alone among industrialized nations in not providing health coverage to all of its citizens. Currently, 46 million Americans lack health coverage.1 Despite repeated attempts to expand health insurance, uninsurance remains commonplace among US adults.
Health insurance facilitates access to health care services and helps protect against the high costs of catastrophic illness. Relative to the uninsured, insured Americans are more likely to obtain recommended screening and care for chronic conditions2and are less likely to suffer undiagnosed chronic conditions3 or to receive substandard medical care.4 Numerous investigators have found an association between uninsurance and death.5–14

The Institute of Medicine (IOM) estimated that 18314 Americans aged between 25 and 64 years die annually because of lack of health insurance, comparable to deaths because of diabetes, stroke, or homicide in 2001 among persons aged 25 to 64 years.4 The IOM estimate was largely based on a single study by Franks et al.5 However, these data are nowmore than 20 years old; both medical therapeutics and the demography of the uninsured have changed in the interim.
We analyzed data from the Third National Health and Nutrition Examination Survey (NHANES III). NHANES III collected data on a representative sample of Americans, with vital status follow-up through 2000. Our objective was to evaluate the relationship between uninsurance and death.
METHODS
The National Center for Health Statistics (NCHS) conducted NHANES III between 1988 and 1994. The survey combined an interview, physical examination, and laboratory testing. NHANES III employed a complex sampling design to establish national estimates of disease prevalence among the noninstitutionalized civilian population in the United States.15 Staff performed interviews in English and Spanish.

The NHANES III Linked Mortality File matched NHANES III records to the National Death Index (NDI). The NCHS’s linkage, which uses a probabilistic matching strategy through December 31, 2000, is described elsewhere.16 The NCHS perturbed the file to prevent reidentification of survey participants. Vital status was not altered in this process. The publicly released data yield survival analysis results virtually identical to the restricted-use NHANES III Linked Mortality File.17

In designing our analysis, we hewed closely to Franks’5 methodology to facilitate interpretation of time trends. We analyzed data for individuals who reported no public source of health insurance at the time of the NHANES III interview. First, we excluded those aged older than 64 years, as virtually all are eligible for Medicare. Of the 33994 individuals participating, 14798 were aged between 17 and 64 years at the time of the interview. In keeping with earlier analyses,5–7,13 we also excluded nonelderly

Medicare recipients and persons covered by Medicaid and the Department of Veterans Affairs/Civilian Health and Medical Program of the Uniformed Services military insurance (n=2023), as a substantial proportion of those individuals had poor health status as a prerequisite for coverage. Of the 12775 participants not covered by government insurance, we excluded 663 (5.2%) who lacked information on health insurance. We excluded 974 of the remaining 12112 who were covered by private insurance or uninsured at the time of the interview because of failure to complete the interview and physical examination. Of the remaining 11138, we included only the 9005 with complete baseline data from both the interview and physical examination in our final analysis (Figure 1). Among those with complete insurance data, those with complete interview and examination data were both less likely to be uninsured (16.4% vs 21.6%; P<.001) and less likely to die (3.0% vs 4.5%; P<.001).