The effect of marijuana on pain response to traumatic injury

There is anecdotal evidence to suggest marijuana users require more medication to manage acute pain, but does the science back this up? A pilot study published today in Patient Safety in Surgery, found that in 261 patients, marijuana users required significantly more narcotics for pain control than non-marijuana users. Here to talk about the study and the medical use of marijuana is author of the article, Kristin Salottolo.

Although the Gold Rush in 1858 is responsible for first putting Colorado on the map, the State’s popularity recently increased with the “green rush” in 2014. On January 1st of that year, Colorado became the first state to legally allow recreational use of marijuana. These days it is nearly impossible to walk down the street without seeing or smelling a pot dispensary.

Even before the green rush began, Colorado was at the forefront of marijuana legalization efforts, first legalizing medical marijuana in 2000. However, more relaxed marijuana laws are not exclusive to Colorado; currently, there are over 30 states with laws allowing the use of medicinal marijuana.

Marijuana is used medically mostly for its antinociceptive (pain relieving, pain sparing) benefits. Studies have also suggested a role for marijuana in treating chronic pain and neuropathic pain. But does marijuana have an effect on acute pain, like that suffered by patients presenting to a hospital after injury?

Anecdotal evidence suggests otherwise. At some of the hospitals that participated in our study, the physicians observed that there has not only been an increase in patients presenting to the emergency department who reported using marijuana, but that marijuana users required more pain medications to manage their pain than the marijuana-naïve counterparts.

We conducted a small, multi-institutional pilot study at four Colorado trauma centers and one trauma center in Texas, a state with strict marijuana laws.

Our research consortium sought to determine if there is an association between pre-injury marijuana use and pain response following traumatic injury. To answer this question we conducted a small, multi-institutional pilot study at four Colorado trauma centers and one trauma center in Texas, a state with strict marijuana laws.

We studied 261 patients that were involved in a motor vehicle crash during a four-month period to determine how many narcotics (total opioid consumption) were required to control pain during their hospitalization, comparing marijuana users to non-marijuana users.

We found that in the majority of patients, marijuana users required significantly more narcotics for pain control than non-marijuana users, both before and after adjustment for confounding variables. Compared to non-marijuana users, daily narcotic use was greater in chronic marijuana users, a 25-37% increase in opioid consumption for marijuana users than non-marijuana users.

We also found that 21% of patients with a motor vehicle crash injury reported using marijuana, including 30% who reported chronic use; marijuana use was reported more frequently in Colorado hospitals (23%-29%) compared to the hospital in Texas (6%); and compared to marijuana-naïve patients, marijuana users tended to be younger and use other drugs besides marijuana.

Only 9% of patients also tested positive for other drugs (i.e. amphetamines, barbiturates, benzodiazepines, cocaine, methamphetamine, or opiates). Interestingly, we found that narcotic consumption was no different in drug users who also used marijuana compared to drug users who did not use marijuana. In other words, the addition of marijuana in the presence of other drugs did not affect pain control with narcotics, but marijuana use in and of itself significantly affected acute pain management and resulted in increased consumption of narcotics compared to patients who did not report using any drugs including marijuana.

To our knowledge, this is the first study to examine the effect of marijuana use and abuse on acute pain management following injury. Because trauma patients commonly have substance abuse issues, our results could have far-reaching implications.

The results of our pilot study were informative, but limited due to the small population of 261 patients. This study should serve as a call to action for more research into whether marijuana legalization has resulted in an increased incidence of traumatic injury, and whether marijuana use results in greater use of narcotics following injury.

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