Is cannabis use associated with less opioid use among people who inject drugs?

Abstract

Background Clinical, experimental, and ethnographic research suggests that cannabis may be used to help manage pain. Ethnographic research has revealed that some people are using cannabis to temper their illicit opioid use. We seek to learn if there is an association between cannabis use and the frequency of nonmedical opioid use among people who inject drugs (PWID). Methods PWID were recruited using targeted sampling methods in Los Angeles and San Francisco, California, 2011–2013. We limited analysis to people who used opioids in past 30 days (N=653). Outcome variable: number of times used any opioids non-medically in past 30 days. Explanatory variable: any cannabis use past 30 days. Statistics: multivariable linear regression with a log-transformed outcome variable. Results About half reported cannabis use in the past 30 days. The mean and median number of times using opioids in past 30 days were significantly lower for people who used cannabis than those who did not use cannabis (mean: 58.3 vs. 76.4 times; median: 30 vs 60 times, respectively; p<0.003). In multivariable analysis, people who used cannabis used opioids less often than those who did not use cannabis (Beta: −0.346; 95% confidence interval: −0.575, −0.116; p<0.003). Conclusions There is a statistical association between recent cannabis use and lower frequency of nonmedical opioid use among PWID. This may suggest that PWID use cannabis to reduce their pain and/or nonmedical use of opioids. However, more research, including prospective longitudinal studies, is needed to determine the validity of these findings.

Nonmedical prescription pain reliever and alcohol consumption among cannabis users

“…We observed that more frequent use of cannabis was associated with more frequent use of NMPR, with findings replicating in 2013 and 2003. Kral et al (2015) reported data somewhat counter to our findings, showing an inverse relationship between the number of times cannabis was used in relation to the proportion of opioid users in each category of marijuana use. Several methodological differences between the two studies may shed light on the sources of these differences.…”

“…Examining levels of use overcomes this limitation by establishing whether a user favors one substance relative to another based on quantity measures. A study by Kral et al (2015) examined the possibility that cannabis may be used as a substitute for opioids by comparing the frequency of use as reported for both substances. The authors found a negative relationship between cannabis use and opioid use, and drew upon those findings to support a substitution hypotheses.…”

Polydrug use and its association with drug treatment outcomes among primary heroin, methamphetamine, and cocaine users

“…In contrast, there appeared to be negative associations between secondary alcohol and marijuana use with primary heroin use. One recent study also reported reduced opioid use frequency among people who inject drugs in California who also used marijuana compared to who did not (Kral et al, 2015). However, the potential role of medical marijuana use as a harm reduction approach among opioid-using populations is still under debate and requires more research (Lucas et al, 2016).…”

High-intensity cannabis use and HIV clinical outcomes among HIV-positive people who use illicit drugs in Vancouver, Canada

“…In light of emerging research in similar settings demonstrating the use of cannabis to curb the frequency of other illicit drug use, including opioid use (Kral et al, 2015; Lau et al, 2015; Lucas et al, 2013; Lucas et al, 2015), it is possible that some individuals engage in daily cannabis use as a means of reducing their use of other illicit drugs. If true, this shift in drug use pattern may be accompanied by a higher likelihood of engaging in ART care and adhering optimally to ART simply due to improved management of higher risk illicit drug use (Palepu et al, 2003; Rosen et al, 2013).…”

“…However, more recent research suggests that high-intensity cannabis use may be linked to poorer HIV treatment outcomes, including exhibiting a detectable viral load (Bonn-Miller et al, 2014). Emerging research also suggests that some PWUD may use cannabis to substitute for higher-risk drug use patterns, including opioid use (Kral et al, 2015; Lau et al, 2015; Lucas et al, 2013; Lucas et al, 2015). In this sense, cannabis use may prove beneficial for TasP efforts among PWUD, given the known association between illicit opioid use with reduced likelihood of adherence to ART (Azar et al, 2015; Jeevanjee et al, 2014; Rosen et al, 2013; Shannon et al, 2005), and subsequent viral treatment failure (Nolan et al, 2011).…”