The study found that avoidable mortality increased in all 50 states and the District of Columbia over the study period, with a national average increase of 32.5 deaths per 100,000 people largely driven by preventable causes. Increases ranged from five avoidable deaths per 100,000 in New York to 100 per 100,000 in West Virginia.

Much of the increase in avoidable mortality was from external causes like traffic accidents, homicides, suicides, and drugs and alcohol. Among external causes, drug-related deaths were responsible for 71% of the increase in avoidable deaths.

The study's authors wrote that their findings raised questions about how effectively the United States spends money on healthcare.

"While other countries appear to make gains in health with increases in healthcare spending, such a relationship does not exist across U.S. states, raising questions regarding U.S. health spending efficiency," the authors wrote.

The study's findings suggest that systemic healthcare problems and inadequate public policy could be contributing to worse outcomes in the United States, according to Irene Papanicolas, lead author of the study and a professor of health services, policy, and practice at Brown's School of Public Health.