Number 2, March 2003



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Jumping to Conclusions: Will Expanding Health Care Insurance Improve the Health of the Uninsured?

Hundreds of studies document that people without health insurance have worse outcomes than those with health insurance. Is this evidence enough to conclude that having health insurance would improve the health of the uninsured?

A review of the research, conducted for The Economic Research Initiative on the Uninsured (ERIU) at the University of Michigan by University of Chicago health economists Helen Levy, Ph.D., and David Meltzer, M.D., Ph.D., reveals that the vast majority of the studies examining the extent to which health insurance can improve health outcomes cannot determine a causal effect because they don't adequately control for other key factors, such as age or income, that may contribute to health status. Only a handful of studies have been designed to show such a causal relationship between health insurance and improved health, while most research merely suggests a correlation exists.

Although extending health insurance can help people access medical care, researchers need to delve deeper to better understand how having health insurance compares to other interventions that can affect health, such as wider access to public health clinics, immunizations, initiatives to curb obesity, and programs to reduce socioeconomic inequities. This will allow policymakers to consider the value of health insurance relative to other interventions that could improve health, and avoid unnecessarily costly and misguided policy interventions that do not best improve health.

"Expanding health insurance is an important policy solution but it fails to get at the root causes of poor health status among some uninsured individuals. As a group, people without health insurance are less healthy than people with coverage, but poor health status is not always attributable to being uninsured. Consequently, interventions other than, or in addition to, insurance expansions may be the most efficient way to improve the health of uninsured individuals. For example, using public dollars to address America's obesity epidemic among school-aged children by subsidizing school lunches and offering more nutritious choices may be a more efficient way to improve the health of uninsured young people. Supporting educational, social, and therapy programs designed to temper rates of drinking, smoking and other high-risk behavior among teenagers may be more effective in improving their health status. Before debating how to make the best use of limited resources, policymakers need better research on the relative contribution of various determinants of health disparities."
From Catherine McLaughlin, Ph.D., Professor at the University of Michigan and Director of ERIU


  • Access to medical care through insurance is one of many factors determining health status. Other indicators include age, stress, income, education level, health behaviors, beliefs about Western medicine, and genetic predisposition to disease.

  • Correlation does not mean causation. Of nearly 1,000 studies showing that people without health insurance have worse health status than those with insurance, less than a dozen are designed in a way to determine if the relationship is causal.

  • Insurance expansion benefits children, elderly. The few studies designed to determine such a causal relationship show that health improvements have occurred for children and seniors under policies that have expanded Medicaid, children's health, and Medicare coverage. But evidence is lacking that health insurance improves the health of non-elderly adults.

Click here for full Q&A with David Meltzer,M.D.,Ph.D.

This Research Highlight is the second in a series of research-based policy documents that will address current questions and issues related to the health care coverage debate. The next Research Highlight will examine what leads some employers to offer and some workers to take employment-based health insurance. Research Highlights can be found on ERIU’s website at .

Click here for other ERIU Research Highlights

Click here for the full paper (Adobe PDF)

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Funded by The Robert Wood Johnson Foundation, ERIU is a five-year program shedding new light on the causes and consequences of lack of coverage, and the crucial role that health insurance plays in shaping the U.S. labor market. The Foundation does not endorse the findings of this or other independent research projects.