Marijuana Associated with Risk of Poor Lung Function Symptoms

Data indicates that smoking marijuana carries distinct associations with a two-fold increased risk of cough, four-fold increased risk of sputum production, and significant risk of other symptoms, according to new meta-analysis.

Thirty states, plus Washington, DC, have legalized medical marijuana, with Oklahoma residents voting strongly in favor of a state question to legalize a medicinal form of the plant in last week’s primary election.

Additionally, multiple institutions have launched ongoing research into the therapy’s potential health benefits. However, marijuana, like tobacco, has been shown to contain some harmful substances, including particulate matter, toxic gases and free radicals. Past studies have also found some evidence linking marijuana use with changes in bronchial inflammation similar to those from tobacco smoke.

A survey conducted by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) in 2015 found that the number of Americans who reported using marijuana within the past year doubled between 2001-2013, increasing from 4.1% to 9.5%.

“Given the rapid expanding of marijuana use, there is a need for large-scale, longitudinal studies,” study author Mehrnaz Ghasemiesfe, MD, San Francisco Veteran Affairs Center, told MD Mag.

Researchers conducted a systematic review of data collected from PubMed, Embace, PsycINFO, MEDLINE, and the Cochrane Library from January 1973 to April 2018. Twenty-two studies were included that reported pulmonary outcomes in adolescents and adults who had reported using marijuana.

Combined analysis of 2 prospective studies showed that marijuana use was associated with an increased risk for cough (risk ratio [RR], 2.04; 95% CI; 1.02 - 4.06) and sputum production (RR, 3.84; 95% CI; 1.62 - 9.07).

An examination of the cross-sectional studies also showed that marijuana use was associated with cough (RR, 4.37; 95% CI; 1.71 - 11.19), sputum production (RR, 3.40; 95% CI; 1.99 - 5.79), wheezing (RR, 2.83; 95% CI; 1.89 - 4.23), and shortness of breath (RR, 1.56; 95% CI; 1.33 - 1.83). There was incomplete data on pulmonary function and COPD, hindering conclusive associations, according to researchers.

Ghasemiesfe said limitations of this study were in examining young populations and low-exposures rates.

“The most important thing we understand from this study is the lack of standardized, marijuana use assessments tools and well-defined studies with robust assessment and long enough duration of follow-up,” Ghasemiesfe said.

“Future studies need to focus on middle-aged to older populations who have been heavier marijuana users to identify its potential effects on lung function and developing obstructive lung disease.”

The study, “Marijuana Use, Respiratory Symptoms, and Pulmonary Function: A Systematic Review and Meta-analysis,” was published online in The Annals of Internal Medicine on Monday.