Cannabinoids, a class of prescription pills that contain synthetically-made chemicals found in marijuana, are associated with a 64% increase in death among older adults with COPD, according to a study published in Thorax. Researchers say it is the first published data on the impact of cannabinoids on the respiratory health of individuals with COPD.

The findings, published Wednesday in Thorax, have significant clinical implications as more physicians prescribe cannabinoids to patients with COPD to treat chronic muscle pain, difficulty sleeping and breathlessness.

The study, led by St. Michael’s Hospital of Unity Health Toronto, found that cannabinoids can contribute to negative respiratory health events in people with COPD, including hospitalization and death. COPD is a progressive lung disease that causes difficulty breathing and chronic productive coughing, and can be associated with a variety of non-respiratory issues, like chronic muscle pain and insomnia.

“Cannabinoid drugs are being increasingly used by older adults with COPD, so it is important for patients and physicians to have a clear understanding of the side-effect profile of these drugs,” said Dr Nicholas Vozoris, lead author, a respirologist at St. Michael’s and an associate scientist at the hospital’s Li Ka Shing Knowledge Institute.

“Our study results do not mean that cannabinoid drugs should be never used among older adults with COPD. Rather, our findings should be incorporated by patients and physicians into prescribing decision-making. Our results also highlight the importance of favoring lower over higher cannabinoid doses, when these drugs actually do need to be used.”

The study analyzed the health data of over 4,000 individuals in Ontario ages 66 years and older with COPD from 2006 to 2016. The data was equally split into two groups: older adults with COPD who were new cannabinoid users and older adults with COPD not using cannabinoids. Older adults in Ontario with COPD who were new cannabinoid users represented 1.1 per cent of the data, which was made available by ICES.

Researchers observed particularly worse health outcomes among patients with COPD who were using higher doses of cannabinoids. Compared to non-users, new higher-dose cannabinoid users had a 178% relative increase in hospitalizations for COPD or pneumonia, and a 231% relative increase in all-cause death.

“Older adults with COPD represent a group that would likely be more susceptible to cannabinoid-related respiratory side-effects, since older adults less efficiently break down drugs and hence, drug effects can linger in the body for longer, and since individuals with COPD have pre-existing respiratory troubles and respiratory compromise,” said Vozoris.

Researchers conducted a sub-analysis to explore what impact cannabinoid drugs versus opioid drugs had on respiratory outcomes among older adults with COPD, since cannabinoid drugs are often prescribed as an alternative to opioids to treat chronic pain. The research team did not find evidence to support that cannabinoids were a safer choice over opioids for older adults with COPD in so far as respiratory health outcomes.