Abstract

Background Previous studies have associated marijuana exposure with increased respiratory symptoms and chronic bronchitis among long-term cannabis smokers.The long-term effects of smoked marijuana on lung function remain unclear.

Methods We determined the association of marijuana smoking with the risk of spirometrically-defined COPD [post-bronchodilator FEV1/FVC<0·7] in 5291 population-based individuals and the rate of decline in FEV1 in a subset of 1285 men and women, aged 40 years and older, who self-reported use (or nonuse) of marijuana and tobacco cigarettes and performed spirometry before and after inhaled bronchodilator on multiple occasions. Analysis for the decline in FEV1 was performed using random mixed effects regression models adjusted for age, gender, and body mass index. Heavy tobacco smoking and marijunana smoking was defined as >20 pack-years and >20 joint-years, respectively.

Results Approximately 20% of participants had been or were current marijuana smokers with most also having smoked tobacco cigarettes (83%). Among heavy marijuana users, the risk of COPD was significantly increased (adjusted odds ratio, aOR, 2.45; 95% CI, 1.55–3.88). Compared to never-smokers of marijuana and tobacco, heavy marijuana smokers and heavy tobacco smokers experienced a faster decline in FEV1 by 29·5 mL·year−1 (p=0·0007) and 21·1 mL·year−1 (p<0.0001), respectively.Those who smoked both experienced a decline of 32.31 mL·year−1 (p<.0001).

Interpretation Heavry marijuana smoking increases the risk of COPD and accelerates FEV1 decline in concomitant tobacco smokers beyond that observed with tobacco alone.

Footnotes

This manuscript has recently been accepted for publication in the European Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article.

Conflict of interest: Dr. Tan reports grants from Canadian Institute of Heath Research (CIHR/Rx&D Collaborative Research Program Operating Grants- 93326) with industry partners Astra Zeneca Canada Ltd., Boehringer-Ingelheim Canada Ltd, GlaxoSmithKline Canada Ltd, Merck, Novartis Pharma Canada Inc., Nycomed Canada Inc., Pfizer Canada Ltd., during the conduct of the study.

Conflict of interest: Dr. Bourbeau reports grants from Canadian Institute of Heath Research (CIHR/Rx&D Collaborative Research Program Operating Grants- 93326) with industry partners Astra Zeneca Canada Ltd., Boehringer-Ingelheim Canada Ltd, GlaxoSmithKline Canada Ltd, Merck, Novartis Pharma Canada Inc., Nycomed Canada Inc., Pfizer Canada Ltd., during the conduct of the study.

Conflict of interest: Dr. Aaron has nothing to disclose.

Conflict of interest: Dr. Hogg has nothing to disclose.

Conflict of interest: Dr. Maltais has nothing to disclose.

Conflict of interest: Dr. Hernandez reports grants from Canadian Institute Health Research, during the conduct of the study; grants and personal fees from AstraZeneca, grants and personal fees from Boehringer Ingelheim, grants and personal fees from GlaxoSmithKline, personal fees from Merck, grants and personal fees from Novartis, grants and personal fees from Takeda, personal fees from Grifols, grants from CSL Behring, personal fees from Pfizer, personal fees from Almirall, outside the submitted work.

Conflict of interest: Dr. Marciniuk has nothing to disclose.

Conflict of interest: Dr. Chapman reports grants from Novartis, grants from Almirall, grants from Boehringer Ingelheim, grants from Forest, grants from GSK, grants from AstraZeneca, grants from Amgen, grants from Roche, grants from CSL Behring, grants from Grifols, grants from Genentech, grants from Kamada, during the conduct of the study; other from CIHR-GSK Research Chair in Respiratory Health Care Delivery, outside the submitted work.

Conflict of interest: Dr. To has nothing to disclose.

Conflict of interest: Dr. FitzGerald has nothing to disclose.

Conflict of interest: Dr. Walker reports grants from Canadian Institute of Health Research, grants from AstraZeneca Canada Ltd, grants from Boehringer Ingelheim Canada, grants from GlaxoSmithKline Canada, grants from Novartis, during the conduct of the study; grants from Respiratory Health Strategic Clinical Network Alberta, personal fees from AtraZeneca, personal fees from GlaxoSmithKline, personal fees from Novartis, outside the submitted work.

Conflict of interest: Dr. Road has nothing to disclose.

Conflict of interest: Dr. Zheng has nothing to disclose.

Conflict of interest: Dr. Zhou has nothing to disclose.

Conflict of interest: Dr. Yau has nothing to disclose.

Conflict of interest: Dr. Benedetti has nothing to disclose.

Conflict of interest: Dr. O’donnell has nothing to disclose.

Conflict of interest: Dr. Sin reports grants from AstraZeneca, during the conduct of the study; grants from Merck, personal fees from Sanofi-Aventis, personal fees from Regeneron, grants and personal fees from Boehringer Ingelheim, grants and personal fees from AstraZeneca, personal fees from Novartis, outside the submitted work.

Full Study At  https://erj.ersjournals.com/content/early/2019/09/11/13993003.00826-2019