States With Medical Marijuana Laws Have Lower Opioid Overdose Rates

Fatal
overdoses involving narcotic painkillers are about 25 percent less
common in states with medical marijuana laws than in states that do
not allow patients to use cannabis for symptom relief, according to
a study
published online today by JAMA Internal Medicine. In 2010
alone, the authors calculate, that difference translated into 1,729
fewer deaths than would otherwise have been expected.

The researchers, led by Marcus A. Bachhuber, an internist at the
V.A. Medical Center in Philadelphia, looked at data for all 50
states from 1999 through 2010, a period when opioid overdose deaths
nearly doubled. That upward trend was less pronounced in the 13
states that enacted medical marijuana laws during those years.
Furthermore, “such laws were associated with a lower rate of
overdose mortality that generally strengthened over time.” On
average, states saw a 20 percent reduction the first year after
implementing medical marijuana laws, a difference that rose to more
than 33 percent by the sixth year. “Although the exact mechanism is
unclear,” Bachhuber et al. conclude, “our results suggest a
link between medical cannabis laws and lower opioid
analgesic overdose mortality.”

The authors suggest a few possible explanations:

Patients with chronic noncancer pain who would have
otherwise initiated opioid analgesics may choose medical cannabis
instead….In addition, patients already receiving
opioid analgesics who start medical cannabis treatment may
experience improved analgesia and decrease their opioid dose, thus
potentially decreasing their dose-dependent risk of overdose.
Finally, if medical cannabis laws lead to decreases in
polypharmacy—particularly with benzodiazepines—in people taking
opioid analgesics, overdose risk would be decreased.

Notably, Bachhuber et al. found that state policies aimed
at preventing nonmedical use of opioids, such as prescription
monitoring programs, were not associated with lower overdose rates.
“If the relationship between medical cannabis laws and
opioid analgesic overdose mortality is
substantiated in further work,” they write, “enactment
of laws to allow for use of medical cannabis
may be advocated as part of a comprehensive
package of policies to reduce the population risk
of opioid analgesics.”

University of Maine psychologist Marie J. Hayes, who
co-authored a commentary
that accompanied the study,
told Reuters that doctors generally have strong misgivings
about recommending marijuana to patients. Still, she said,
Bachhuder et al.’s findings could be important. “We don’t put
[marijuana] in Rite Aid because we’re confused by it as a society,”
she said. Yet “everything we’re doing [to reduce opioid overdoses]
is having no effect, except for in the states that have implemented
medical marijuana laws.”

[Thanks to Paul Armentano for the tip.]