Recent marijuana use may have an effect similar to recent tobacco use with regard to decreased production of exhaled nitric oxide (eNO), but a very different effect on forced vital capacity (FVC), according to the results of a study published in Chest.
Dr. Stefania I. Papatheodorou from the Cyprus International Institute for Environmental and Public Health, Limassol, Cyprus, in association with the Harvard T. H. Chan School of Public Health, and her colleagues conducted a retrospective analysis of National Health and Nutrition Examination Survey (NHANES) data collected from 10,327 people aged 18-59 years between 2007 to 2012. Respondents completed a questionnaire on illicit drug use and were given a physical examination. Outcomes of interest for this study were eNO levels and pulmonary function measurements including the forced expiratory volume in 1 second (FEV1), FVC, the FEV1/FVC ratio, and the average forced expiratory flow during the mid (25%-75%) portion of the FVC (FEF25%-75%) (Chest. 2016 Jan 16. doi: 10.1016/j.chest.2015.12.033).
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The population available for analysis included 4,797 people who reported never having used marijuana, and 4,084 who reported past use. The recent users were divided into two groups; 555 and 891 respondents who reported using marijuana 5-30 days and 0-4 days before their examinations, respectively. The study results from age-adjusted analyses standardized to the 2000 U.S. Census population indicated that both past and current users had significantly lower eNO levels (in parts per billion) than those that had never used (all P less than .001). The same analysis demonstrated that FEV1, FVC, and FEV1/FVC ratios were all higher in current and past users than in never users (all P less than .001).
Using a multivariable model adjusted for age, sex, race/ethnicity, height, education level, income, marital status, asthma, tobacco use in pack-years, smoking category, and body mass index, both the 0-4 day users and the 5-30 day users showed significantly decreased eNO levels, compared with never users (-7%, 95% confidence interval -12% to -2%, P = .03; -13%, CI -18% to -8%, P less than .001, respectively). Additionally, recent users in the 0-4 day group had significantly higher FEV1 measures than never users (89 mL, CI 29-150, P = 0.005), as well as lower FEV1/FVC ratios (-.02, CI –.03 to –.01, P = .003).
Regarding the broader implications of their study findings, Dr. Papatheodorou and colleagues stated, “Given that nitric oxide plays a role in inflammatory and immune defense pathways in the respiratory system and is a mediator of vasodilation in the pulmonary and systemic vasculature, it would be useful to further explore the associations between marijuana use and vascular and pulmonary function in randomized trials.”
Dr. Mary B. Rice received funding from the Institute for Environmental Sciences. The other authors reported no conflicts of interest.