A growing body of research suggests that a major part of Obamacare, the Medicaid expansion, is playing a significant role in fighting the deadly and growing opioid epidemic.

The latest study, published in Health Affairs by Brendan Saloner, Rachel Landis, Bradley Stein, and Colleen Barry, found that after West Virginia expanded Medicaid, the number of people diagnosed for opioid use disorder under the public insurance program rose — and, crucially, the number of people on buprenorphine, one of two gold-standard medications for opioid addiction, went up as well.

This is particularly pertinent for West Virginia. It’s the state with the highest drug overdose death rate in the country, at 57.8 per 100,000 people in 2017. The next highest state was Ohio, with a drug overdose death rate of 46.3.

The Health Affairs study suggests that the Medicaid expansion, which began in 2014, helped get more people into treatment. The number of people under the Medicaid expansion diagnosed with opioid use disorder more than doubled between January 2014 and December 2016, and the number of people on buprenorphine treatment increased sixfold.

Studies show buprenorphine and methadone reduce the mortality rate among opioid addiction patients by half or more and keep people in treatment better than non-medication approaches.

The changes weren’t even across all groups. For example, non-Hispanic white enrollees were more likely to get on buprenorphine than their Hispanic and black counterparts.

The study has a few limitations. For one, it can’t definitively prove all these people are getting into treatment for the first time because there’s no data for the population before enrollment to Medicaid. West Virginia’s experience also may not track with that of other states, since it has relatively high uninsured rates and a particularly bad opioid crisis.

The study comes as President Donald Trump continues his efforts to repeal Obamacare, which could cost millions health coverage, and as Republicans continue advocating against Medicaid in general. But the study shows Obamacare repeal could scale back a tool that’s helping fight a public health crisis that’s now killing tens of thousands of Americans every year.

Obamacare has helped confront the opioid epidemic

The new study is the latest in a growing body of research to suggest that the Medicaid expansion and Obamacare more broadly are helping combat the opioid epidemic. One 2018 study, in JAMA Network Open, found that the Medicaid expansion did not lead to more opioid painkiller prescriptions, but did lead to more buprenorphine prescriptions.

Another 2018 study in Health Affairs concluded that Obamacare “may have prompted state Medicaid programs to expand addiction treatment benefits and reduce utilization controls in alternative benefit plans.”

And a 2017 analysis, from researchers at Harvard Medical School and New York University, found that without Obamacare, an additional 220,000 people with opioid use disorders would lose insurance coverage to pay for treatment.

To some degree, this is common sense: An expansion in health insurance has made it easier for some people to pay for a form of health care.

But some Republicans, led by Sen. Ron Johnson (WI), have tried to argue the opposite — that the Medicaid expansion has made the opioid crisis worse. Johnson held a hearing and issued a report last year making this claim.

The claim, first popularized in conservative media: After Obamacare encouraged states to expand Medicaid to include everyone at or below 138 percent of the federal poverty level (around $16,750 a year for an individual), more people obtained access to opioid painkillers, since they now could get to doctors to prescribe the drugs and had a health plan to pay for the opioids. And that may have led them to addiction or, at the very least, made opioids more available to misuse and sell in illicit markets.

The evidence suggests that’s not the case. The study in JAMA Network Open, in particular, found that opioid painkiller prescriptions didn’t seem to increase as a result of the Medicaid expansion, even as prescriptions for buprenorphine treatment rose thanks to the expansion.

Johnson’s claim also conflicts with the chronology of the opioid epidemic. Medicaid didn’t expand under Obamacare until 2014 — well after opioid overdose deaths started rising (in the late 1990s), after the Centers for Disease Control and Prevention in 2011 declared the crisis an epidemic, and as the crisis came to involve illicit opioids, such as heroin and fentanyl, more than conventional opioid painkillers.

Meanwhile, experts have long argued for a federal investment in the tens of billions of dollars in addiction treatment. (For reference, a study from the White House Council of Economic Advisers linked a year of the opioid crisis to $500 billion in economic losses.) That could help fill a huge gap in treatment today: Federal data suggests one in 10 people with any substance use disorder and one in five people with an opioid use disorder get specialty treatment, in large part due to a lack of access to care.

Some of that investment could come through grant programs dedicated to the crisis or new safety net programs for addiction treatment. But a lot of it could be done through Obamacare or other expansions in access to health care; after all, if addiction really is a medical condition, as experts and advocates argue, then it should be treated through the traditional health care system just like any other disease.

The West Virginia study suggests that’s how the Medicaid expansion is working in the real world, as more people get insurance to pay for treatment and then actually get into treatment. But if people lose that insurance, they could be left stranded — leaving them without the care they need to fight their addiction, as America deals with its deadliest drug overdose crisis in history.

For more on how Medicaid could help combat the opioid epidemic, read my in-depth report on Virginia’s unique Medicaid experiment.