Heroin use has spiked in the US, and some critics have charged that policy changes are to blame. Not so, say a group of government researchers, who exonerate the agencies they work for in a paper published yesterday. Outside drug use researchers find the paper’s claims debatable.

The authors of yesterday's paper "glossed over the negative aspects of these programs," says Ted Cicero, a neuropharmacologist at Washington University. Abuse deterrent drug formulations "are useful overall, but they are not the whole answer — and some users will as a result shift to other drugs including heroin."

Cicero also objects to the way one of his studies was interpreted by the authors of the paper. "They falsely conclude that we believe [abuse deterrent formulations] are not useful, and were solely responsible for the increase use of heroin," he told The Verge. This alone was not the only cause for the rapid rise in heroin across the country, "as we made clear" in the study.

Wilson Compton, deputy director of the National Institute on Drug Abuse and a co-author of the paper told The Verge in response that his team "thought that was what [Cicero] suggested in his earlier study, but it sounds like he and I agree that it's more complicated." Compton also says that what he thought "was crystal clear people have not always gotten right." Prescription painkiller use "is a risk factor for the transition to heroin, but the policies related to reducing the excess prescribing do not seem to be responsible for pushing the population toward heroin," he says.

Cicero wasn't the only expert to question the paper's conclusions. "I'm skeptical of the idea that heroin market forces alone are the cause leading to recent increases in heroin," says Pedro Mateu-Gelabert, a drug use researcher at New York University. It's conceivable that many people who developed painkiller dependency transitioned to heroin prior to the restrictions because heroin costs less, he says. But such a transition doesn't preclude the possibility that restriction polices could accelerate that transition for painkiller dependent individuals. "Both phenomena are not mutually exclusive."

For Joseph Palamar, a drug use researcher also at New York University, the policies are "a double-edged sword." Making it harder for people to obtain prescription painkillers for non-medical uses might prevent people from misusing the drugs, which would therefore reduce the chances of the individual moving onto heroin. But "cutting off the pill supply from someone addicted to opioid pills also increases the chances that he or she will move onto heroin, which is cheaper and more available."

In response, Compton told The Verge that he can't rule out the possibility that the policies "play any role in some individuals. "But the policies neither played a positive, nor particularly negative role in terms of the transition to heroin."

Not everyone questions the paper's conclusions. "This paper is fascinating. I can't wait until it's out so I can send it to other people," Caleb Alexander, co-director of the Center for Drug Safety and Effectiveness at Johns Hopkins University, told The Verge before the paper was published. Although he appreciates people's concerns about potential unintended effects of these types of policies, he doesn't "feel like the policies underlie increases in heroin use."

There is some evidence to suggest that prescription painkiller policies have been successful at their intended goal. Between 2010 and 2012, the rate of painkiller prescribing stabilized in the US and even declined in some areas, the authors note. Still, it's clear that not everyone thinks the policies were harmless.

The importance of balancing availability of options for pain with the excess availability of painkillers due to overprescribing is mentioned in the paper, Compton says. He also states that no policy is perfect. "I'm a firm believer that we will probably never get policies 100 percent correct, and so we always need to pay attention to how to improve them." But Alexander says that the dilemma is a false one. "I'm not aware of any rigorous empirical evidence" that shows that the policies caused substantial barriers to legitimate painkiller use.

The debate over prescription painkiller policies won't end with this paper. It may take a lot more time to find out just how large (or how small) of an impact they've had on American drug use and American pain. Regardless, the US has an opioid misuse problem that doesn't seem to be going away. So for Mateu-Gelabert, the bottom line is that drug prevention efforts should go further. And expanding safe injection education and syringe access are "critical next steps in preventing the current spread of hepatitis C, and possibly HIV, among young opioid injectors."