Health insurance and mortality. Evidence from a national cohort

Abstract

Objective: To examine the relationship between lacking health insurance and the risk of subsequent mortality.

Design: Adults older than 25 years who reported they were uninsured or privately insured in the first National Health and Nutrition Examination Survey, a representative cohort of the US population, were followed prospectively from initial interview in 1971 through 1975 until 1987.

Participants: Complete baseline and follow-up information was obtained on 4694 (91%) persons of the 5161 who reported not receiving publicly funded insurance at baseline.

Main outcome measure: The relationship between insurance status and subsequent mortality was examined using Cox proportional hazards survival analysis. The analysis adjusted for gender, race, and baseline age, education, income, employment status, the presence of morbidity on examination, self-rated health, smoking status, leisure exercise, alcohol consumption, and obesity. The effects of interactions between insurance and all other baseline variables were also examined.

Results: By the end of the follow-up period, 9.6% of the insured and 18.4% of the uninsured had died. After adjustment for all other baseline variables, the hazard ratio for lacking insurance was 1.25 (95% confidence interval [CI], 1.00 to 1.55). The effect of insurance on mortality was comparable to that of education, income, and self-rated health. There were no statistically significant (P < .05) interactions.

Conclusions: Lacking health insurance is associated with an increased risk of subsequent mortality, an effect that is evident in all sociodemographic health insurance and mortality groups examined.