Some of our favorite health researchers—Ben Sommers, Atul Gawande, and Katherine Baicker–published an article this week in the New England Journal of Medicine sharing the most recent evidence on the effects of health insurance coverage, especially Medicaid coverage, to inform the national debate on health care. They review the most rigorous studies on how health coverage affects access, utilization, outcomes, and mortality. They find that health coverage expansions produce benefits to health and likely lead people to live longer. On the other hand, they find that coverage reductions lead to significant harms to health, particularly for those with lower incomes and chronic health conditions.

The authors set the stage for their article by reminding us that the primary role of health insurance is to protect families from financial devastation. Studies show that Medicaid reduces medical bills sent to collection, out-of-pocket medical spending, catastrophic medical spending and bankruptcies. Health insurance reduces the risk of large, unanticipated medical costs to families. You can read more about Medicaid’s role providing families with economic security here.

The researchers found that coverage, specifically Medicaid, leads to improvements in access to care and utilization of care. Medicaid is associated with higher rates of having a usual source of care and a personal physician. It also increased preventive office visits and some preventive screenings, including cancer screenings and lab tests. Medicaid coverage increased outpatient utilization and prescription drug utilization. It also increased rates of diagnosing and treatment of chronic conditions. One area that has ambiguous results is emergency department use, which researchers have found mixed evidence on; some studies show an increase and others a decrease.

Across multiple studies, the researchers found evidence that coverage improves self-reported health. Their evidence also indicates that having any type of health insurance is beneficial, and that it does not seem to matter much whether it is public or private. The researchers conclude that any argument stating health insurance doesn’t improve health is simply inconsistent with the evidence.