Impact of Changes in Unregulated Drug Supply on Risk of Overdose Death

"The estimates presented in this article find important evidence of the potential consequences of the rapid expansion of the MA supply in Ohio, which can help inform the public health consequences of a similar expansion across the US. We find that relatively more MA detected by crime labs is either unrelated to or associated with a small, but measurable decrease in the overall risk of unintentional overdose death. This is not to say that MA is safe or cannot cause overdose deaths. Our findings are not that the combination of MA and fentanyl is in fact safer than fentanyl on its own. As our estimates are only showing averages, it could certainly be the case that an increase in MA availability makes illicit drug consumption more deadly for some people or at particular dose levels. Rather, given the context of extremely dangerous synthetic opioids, our estimates should be interpreted as showing that a relative increase in the availability of less deadly drugs, especially if they are replacing synthetic opioids, may reduce the overall number of overdose deaths, at least in the short-run. Furthermore, we do not investigate the substantial, non-fatal health consequences of MA use such as psychosis and cardiovascular disease, which may be increasing even if deaths decline.

"The exact mechanism linking MA to overdose deaths is not clear. Is it that MA use directly reduces the risk of overdose when used concurrently with opioids? If the animal data are applicable to humans, is MA co–use with fentanyl reducing opioid overdose risk at some doses and increasing it at others? Is it that MA use allows people to lengthen the duration between opioid use or substitute away from opioids entirely? This is supported by recent research showing that some people find MA helpful for managing opioid withdrawal (Ondocsin et al., 2023). Or is MA supply simply correlated with a reduction in overdose death, and we are missing a key unobservable omitted variable, such as greater migration to substance use treatment, that is positively correlated with MA supply?"