Use of Cannabis Linked to High Risk of Prevalent Asthma: New Findings

Asthma is more common among individuals who have used cannabis in the past 30 days compared to those who have not, according to new findings published in the journal Preventive Medicine.

Researchers also reported a dose-response relationship between the number of days per month of cannabis use and likelihood of current asthma, with more days of use associated with greater odds of current asthma, even after adjusting for demographic characteristics and concurrent cigarette smoking.

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In the full study sample of more than 32 000, researchers reported the prevalence of current asthma as 7.4%. Among individuals who reported any past 30-day cannabis use, current asthma prevalence was higher (9.8%) than among those who did not (7.1%), translating to a 43% increase in the odds of current asthma among the former group vs the latter.

Among study participants who reported using cannabis on 20 to 30 of the past 30 days, the odds of current asthma increased to 73% compared to those who reported no use. The odds of asthma in persons who reported using blunts (cannabis smoked in a hollowed-out cigar) in the past 30 days was more than 2-fold, according to the findings. Moreover, all associations remained significant after multivariable adjustment, including for use of tobacco cigarettes.

Associations between cannabis use and asthma are both poorly understood and understudied and particularly relative to the body of evidence linking cigarette smoking and asthma, lead researcher Renee Goodwin, Department of Epidemiology and Biostatistics at the Graduate School of Public Health and Health Policy, The City University of New York, and colleagues wrote. “With the growing use of cannabis, understanding potential links between cannabis use and asthma is increasingly relevant to population health,” authors stated.

The investigators’ dual objectives with this study were to estimate asthma prevalence among persons with and without past 30-day cannabis use and to discern evidence of a dose-response relationship between frequency of cannabis use and asthma prevalence.

Goodwin and colleagues tapped data from the 2020 National Survey on Drug Use and Health, which is conducted annually and a source of national cross-sectional data on tobacco, drug use, mental health, and related issues. The 2020 public use data file included data from 32 893 respondents aged 12 years and older, according to the study.

Study variables were current asthma, current cannabis use/use in the past 30 days, current blunt use/use in the past 30 days, current cigarette smoking during the past 30 days; covariates included age, sex, income, marital status, income, and race and ethnicity.

The investigators calculated current asthma prevalence in persons with and without past 30-day cannabis use and, using logistic regression, quantified associations between use of cannabis products and current asthma before and after controlling for covariates.

FINDINGS

Of the original sample of 32 893, 2611 reported current asthma and this group had twice as many women as men. The numerically largest age group of those with current asthma was aged 18 to 25 years and the majority of the cohort identified as non-Hispanic White.

The odds of current asthma were higher for participants with past 30-day use of cannabis vs those without (OR 1.43, 95% CI, 1.16-1.78; P = .001), an association that remained significant after adjusting first for sociodemographic variables (adjusted OR 1.38; 95% CI, 1.11-1.73) and then with cigarette use added (aOR 1.35; 95% CI, 1.07-1.69), according to the study results.

Similarly, the odds of current asthma among those reporting between 20 and 30 days of cannabis use in the past 30 days were higher compared to those who did not use cannabis (OR, 1.73; 95% CI, 1.29-2.3). This association also persisted after adjustment for all sociodemographic variables and cigarette use. Of note, the investigators did not find statistical significance for the associations among individuals with current asthma who reported using cannabis fewer than 20 days per month.

Goodwin et al found similar associations between asthma and 30-day use of blunts that remained significant after adjustments for both sociodemographics and cigarette use, although odds of asthma were higher and also higher with fewer monthly days of use. Those with only 6 to 19 days of past 30-day blunt use were significantly more likely to have current asthma (OR 1.85; 95% CI, 1.07-3.21), relative to those with no use. Further, individuals using blunts on 20 to 30 of the past 30 days were reported more than 2 times as likely to have asthma (OR, 2.20, 95% CI, 1.35-3.60). No association was observed between blunt use on fewer than 5 days per month and current asthma.

The researchers concluded there was a positive linear relationship between prevalent asthma and frequency of both cannabis and blunt use (P <. 001).

“In sum, current asthma appears significantly more common among individuals ages 12 and older who report past 30 days of cannabis use in the US with findings suggestive of a dose-response relationship between frequency of cannabis use and asthma prevalence,” wrote Goodwin et al. "The relative lack of impact of change in the relationship after adjusting for cigarette use and the findings show that the more frequent the use, the higher the likelihood of asthma is which is suggestive of a direct link, but by no means conclusive,” they concluded, calling for future research.

Source: Goodwin RD, Zhou C, Silverman KD, Rastogi D, Borrell LN. Cannabis use and the prevalence of current asthma among adolescents and adults in the United States. Prevent Med. 2024;179:107827. doi:10.1016/j.ypmed.2023.107827