A big Obamacare policy could help fight the heroin epidemic. Politics is holding it back.

With an opioid painkiller and heroin epidemic killing tens of thousands each year, lawmakers across the country have talked at length about dealing with the crisis by boosting access to drug abuse treatment.

"In Tennessee, we have a problem with prescription drug abuse and it's going to take all of us working together to tackle it," Tennessee Gov. Bill Haslam said, while unveiling a plan that vowed to increase access to treatment for drug abuse.

But Tennessee, like 18 other states, is rejecting a policy that would provide access to treatment to potentially hundreds of thousands of opioid abuse patients: the Medicaid expansion.

Under Obamacare, the federal government encourages states to expand Medicaid, the public health insurance program for the poor, to cover anyone at up to 138 percent of the federal poverty level. This would give many low-income people a way to pay for drug treatment. And it'd be a good deal for states: The federal government would pay for more than 90 percent of the expansion, compared to the typical 60 percent it pays for all of Medicaid.

Medicaid plays a huge role in paying for drug abuse treatment. According to a 2014 study by Truven Health Analytics researchers, Medicaid paid for about 25 percent — $7.9 billion of $31.3 billion — of projected public and private spending for drug abuse treatment in 2014. That makes it the second biggest payer for drug abuse treatment spending after all local and state government programs.

But despite Obamacare's funding incentives to expand Medicaid, many states haven't expanded. Conservatives argue that even the 10 percent they would have to pay for expanding Medicaid is too costly, especially since they view Medicaid as a dysfunctional entitlement program and Obamacare, the measure funding the expansion, as a broken law. (Even if Medicaid has problems, research shows it's better than no insurance at all.)

So 19 states, mostly under Republican control, haven't expanded Medicaid.

This leaves a lot of Americans with drug use disorders stranded without access to care — even as there's a policy tool to take care of these people.

The Medicaid expansion can help increase access to treatment in two big ways

The opioid epidemic has exposed a massive gap in the American health care system. According to 2014 federal data, at least 89 percent of people who met the definition for a drug use disorder didn't get treatment. Patients with drug use disorders also often experience weeks- or months-long waiting periods for care. (Imagine having to wait weeks or months to get care for any other illness with deadly outcomes, like heart disease or cancer.)

"What we have right now is a population of people out there who have serious problems with opioid use disorder … and they don't have access right now to effective treatment," Brendan Saloner, a researcher at Johns Hopkins University, said. "What the Medicaid expansion does is create an opportunity to intervene with these people in order to get them into treatment resources that they otherwise would not be able to access without health insurance."

There are two big ways the Medicaid expansion could help fill the gap:

1. It gives people insurance they can use to pay for drug abuse treatment. According to a March report from the Department of Health and Human Services, about 1.9 million uninsured low-income people with mental illness or drug use disorders live in states without the Medicaid expansions. (The report did not elaborate just how many have a drug use disorder specifically, but it's likely in the hundreds of thousands.)
2. It might encourage more treatment facilities to open up. The idea: If a state expands Medicaid, more treatment facilities may open up in those locations since they know they'll have paying customers. Saloner, who's working on a study related to this issue, said there's "some evidence" that insurance expansions can cause "shifts in the market for treatment."

What's more, the evidence shows getting people into treatment for opioid abuse could prevent other bad outcomes, such as hepatitis or HIV infection from repurposing needles used to inject heroin. Those gains, Saloner said, are so big that drug abuse treatment "could in fact pay for itself within the Medicaid budget." (The research backs up this idea.)

Medicaid is also expected to become more important for drug abuse treatment over time. Previously, the federal Substance Abuse Prevention and Treatment block grant was the big source of funding for such treatment, but it hasn't kept up with inflation over the past few years. "The fate of the population who have these problems is now much more tied and going to keep getting more and more tied every single year to whether or not Medicaid is available," Keith Humphreys, drug policy expert at Stanford University, said.

The expansion wouldn't solve the opioid epidemic entirely. After all, several of the states that are suffering the worst from the crisis — West Virginia, New Hampshire, New Mexico — have already expanded Medicaid. Fully addressing the crises in these states will require a much more comprehensive plan that boosts treatment options across the board.

Still, it's likely these states' crises would be worse without the expansion. "A lot of people don't have good employment, which means they're not going to be getting insurance through their employer," Humphreys said. "So where else are they going to get it?"

Other states hit by the epidemic (particularly Utah, Maine, Missouri, and some in the South), haven't expanded Medicaid. And with overdose deaths climbing every year in the past several years — hitting an all-time record in 2014 — it's likely the crisis will only get worse over time across the country, making the Medicaid expansion more necessary.

Yet political opposition remains strong, even as the opioid epidemic draws bipartisan attention. To many Republicans, Medicaid is a dysfunctional program that needs to be wholly restructured or repealed. The idea of expanding it, then, seems contrary to their interests.

Debates over the Medicaid expansion make it harder to talk about improving Medicaid policies for drug abuse

The Medicaid expansion, while important, is one part of much bigger issues regarding Medicaid and public health. After all, even in states that expanded Medicaid, there's still a dearth of access to high-quality addiction treatment.

As one example, many people with insurance often end up on waiting lists spanning weeks or months just to get into drug use treatment. "There's the broader capacity issues that exist that are somewhat unique to addiction treatment," Saloner said. "Even with greater revenue opportunities, there's a shortage of qualified professionals who could meet potential new demand in these states."

That's not even getting into the debate about the quality of treatment. Many treatment facilities are still based on 12-step programs, like Alcoholics Anonymous, that have a weak empirical basis. This doesn't mean these programs don't work for some people, but they don't appear to work for a lot of people.

Yet debating whether states should expand Medicaid, Harold Pollack at the University of Chicago argued, holds back conversations about how to improve care. "Without the expansion, we get bogged down in questions about how to pay for treatment instead of how to make it work," he said.

Many state Medicaid programs, for instance, don't cover the most effective form of care for drug abuse: medication-assisted treatment.

In medication-assisted treatment, opioid abuse patients are given drugs that safely supplant their more dangerous drug use. When taken as prescribed, these drugs can eliminate someone's cravings for opioids and withdrawal symptoms without the kind of euphoric high that heroin or traditional painkillers cause. This makes it easier for someone to stop using opioid painkillers and heroin, since they don't have to deal with the withdrawal symptoms or cravings that often lead to relapse. And it can be paired with other treatment options, such as therapy and group sessions.

Right now, there are two big opioid abuse medications: buprenorphine and methadone. Buprenorphine is offered in take-home doses, while methadone is usually administered once a day in a clinic.

These two drugs have been well vetted: Decades of research have deemed them effective for treating drug abuse. The Centers for Disease Control and Prevention, National Institute on Drug Abuse, and World Health Organization all acknowledge their medical value.

But states vary widely in whether they even cover these drugs: Saloner's study found that all states cover buprenorphine to some extent, but 17 don't cover methadone.

And without support from Medicaid, the research shows these highly effective drugs are less accessible. A 2016 study by Saloner, Kenneth Stoller, and Colleen Barry found Medicaid enrollees in opioid addiction treatment and in a state Medicaid program that offers methadone treatment are nearly three times as likely to be in medication-assisted treatment for opioids than enrollees in states that offer no methadone coverage through federal funds.

Even state programs that do cover the medications tend to put extra restrictions on their availability. For example, some state Medicaid programs place quantity or time limits on buprenorphine. Given that drug addiction can be a lifelong condition, this can leave a patient stranded without necessary care — and perhaps cause him to relapse.

"Increasingly, we're beginning to understand that having someone on medication like buprenorphine for longer tends to be associated with better outcomes," Bradley Stein, a researcher at the RAND Corporation, said. "If you go back to when it first came out in 2003 or 2004, you can find various documents saying, 'We should be treating people for six months, and then we can get them off of it.' But increasingly we've learned that that's not true."

So why do many states' Medicaid programs fail to cover methadone and put big restrictions on buprenorphine? The big concern is these drugs will prove costly to Medicaid. There are also suggestions that using medication to supplant heroin or opioid painkillers is "replacing one drug with another." But these medicines are effective for treating drug abuse, safer than heroin and opioid painkillers when taken as prescribed, and, again, can essentially pay for themselves.

This is just one example of the many questions over public health policy more broadly, especially in the light of the opioid epidemic. There are still debates about improving Medicaid's structure and quality, expansion or not. There are questions on how drug use disorders should be treated outside of Medicaid — and the US's inadequate mental health care system more broadly. But it's hard to get to those issues if the political discussion remains stuck on whether it should pay for existing programs, much less if it should build more comprehensive public health policies.