Ironman at Political Calculations performs a simple analysis that yields an interesting conclusion:
Beginning in 2014, millions of lower income-earning Americans became eligible to have fully government-subsidized health insurance coverage through the U.S. government's Medicaid welfare program thanks to the expansion of eligibility for that program provided for by the Affordable Care Act (ACA), which is more popularly known as Obamacare. Unfortunately, that expanded access to health care may very well have caused an increase in death rates due to drug overdoses in the United States to such a degree that the overall estimated life expectancy of Americans has declined.
He explicitly states that a richer analysis should consider possible confounders. But this is a fine start.