Older adults with chronic obstructive pulmonary disease who began using synthetic cannabinoids showed a 64% increase in all-cause mortality, compared with nonusers, findings from a large study have shown.

Synthetic cannabinoids drugs, such as nabilone and dronabinol, have been approved by the Food and Drug Administration for nausea and vomiting caused by chemotherapy. But their off-label use by adults with COPD to help manage chronic musculoskeletal pain, insomnia, and refractory dyspnea is on the rise, wrote Nicholas T. Vozoris, MD, of the University of Toronto and colleagues.

Cannabinoids may actually contribute to negative respiratory outcomes among individuals with COPD through several possible mechanisms including causing sedation, inducing anxiety, and provoking respiratory muscle weakness, they said.

“Possible adverse respiratory effects of cannabinoids may occur with greater likelihood among older adults (in whom COPD is more prevalent), as this group is known to less efficiently metabolise drugs,” they noted.

In a retrospective, population-based cohort study published in Thorax the researchers identified 185,876 adults aged 66 years and older with COPD using health administrative database information from 2006 to 2016. New cannabinoid users (those starting nabilone or dronabinol) were matched with control nonusers (defined as new users of noncannabinoid drugs). Individuals receiving palliative care, or having a diagnosis of cancer or HIV, were excluded because these are settings where synthetic cannabinoids may be prescribed for nausea or vomiting, and these patients are more likely to be in a poorer state of health.

Overall, new cannabinoid users had significantly higher all-cause mortality rates, compared with nonusers (hazard ratio, 1.64). The effects was greater in high-dose users.

Daniel R. Ouellette, MD, associate professor of medicine at Wayne State University and a senior staff physician at Henry Ford Hospital, both in Detroit, commented that this study has value for clinicians. “Many states are liberalizing cannabinoid use, and it is important to know the health effects of this type of drug on patients with chronic respiratory disease,” he noted. “The study is somewhat surprising. While one might have expected adverse consequences in patients with COPD who inhaled smoke from cannabinoids, it is somewhat unexpected that oral use would be associated with adverse consequences.”

He added, “Pain in older adults is a complex problem. Cannabinoids are often recommended for pain in the general community, but pain per se is not a primary symptom for most patients with COPD from their respiratory problems. Physicians treating patients with COPD should diagnose the cause of the pain and provide appropriate treatment.”

Dose Makes a Difference

All-cause mortality increased by 231% and hospitalization for COPD or pneumonia increased by 178% among new users of higher-dose cannabinoids, compared with nonusers. Higher dose was defined in this study as more than 1.5 mg/day of nabilone.

No significant differences appeared in new users vs. nonusers in hospitalization for COPD or pneumonia at lower doses, and no significant differences appeared overall in outpatient respiratory exacerbations, emergency department visits for COPD or pneumonia, or COPD- or pneumonia-related mortality.

Potential Limitations and Implications

“The fact that COPD- or pneumonia-related mortality was not observed to occur with significantly greater rates among cannabinoid users with COPD may suggest that the increased all-cause mortality finding was not being driven by adverse respiratory-related drug effects, as we hypothesized, and instead was possibly a result of unresolved confounding,” the researchers noted.

The study findings were limited by several factors including the inability to prove causation in an observational study, and the potential for confounding based on unmeasured differences between cannabinoid users and nonusers, the researchers said.

“Our findings may not be generalizable to all individuals with COPD, as our study included only those aged 66 years and older, and our COPD identification algorithm, while highly specific, had modest sensitivity,” they added.

However, the results were strengthened by the large study population and suggest that cannabinoids are not contraindicated for older adults with COPD, the researchers said. “There can be legitimate reasons for using cannabinoids in this population, such as to help treat chemotherapy-related nausea and vomiting, and possibly for end-of-life care,” they emphasized.

The study findings serve to inform clinicians of the significantly increased mortality risk when older adults with COPD initiate cannabinoids, and “this information should be discussed with patients and incorporated in prescribing decision-making and management plans,” along with consideration of using lower doses when possible to minimize adverse events, they concluded.

The study was supported by The Lung Association–Ontario Grant Review/Grant-In-Aid. The researchers had no financial conflicts to disclose.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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