The investigation by Tan et al. [1] addresses an important question regarding the impact of marijuana smoking in middle-aged and older individuals and the relative risk for developing COPD and an accelerated rate of decline in lung function. The importance of this question is underscored by the spreading legalisation of marijuana and the likely impact on its use in both older and younger persons. The authors approached this question using data from a Canadian cross-sectional population-based prevalence study of COPD carried out in subjects ≥40 years (the COLD cohort) and a selected subsample who were followed for up to 4 years and either had physiological evidence of COPD (forced expiratory volume in 1 s (FEV1) to forced vital capacity ratio <0.70) or served as age- and gender-matched control never and ever smokers with normal lung function (CanCOLD cohort). Since the vast majority (83%) of marijuana smokers in their study also smoked tobacco, the analysis was carried out by adjusting for the concomitant use of marijuana in the dual smokers. Dose–response was analysed by categorising the smokers using three levels of cumulative life-time exposure defined by the number of pack- or joint-years (mild, 1–5; moderate, >5–20; and heavy, >20), and the level of exposure, along with other influential covariates, was adjusted for in the analyses. In their cross-sectional study the authors found that heavy marijuana smoking (>20 joint-years) was associated with spirometrically defined COPD, while in their longitudinal study heavy marijuana smokers were found to experience a substantially faster annual rate of FEV1 decline (nearly 30 mL·yr−1 compared to never smokers of either substance) that was even faster than the decline observed in the heavy tobacco smokers (slightly more than 20 mL·yr−1). The report by W.C. Tan and co-workers raises important questions regarding the impact of marijuana smoking on lung function in older individuals but fails to directly answer them http://bit.ly/2LP2AYi

中文翻译：

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吸食大麻对老年人肺功能的影响

Tan等人的调查。[1] 解决了一个重要问题，即吸食大麻对中老年人的影响以及发生 COPD 的相对风险和肺功能加速下降的速度。大麻合法化的普及及其对老年人和年轻人使用大麻的可能影响凸显了这个问题的重要性。作者使用加拿大横断面基于人群的 COPD 患病率研究的数据来解决这个问题，该研究在 40 岁以上的受试者（COLD 队列）和一个选定的子样本中进行，这些子样本被随访长达 4 年，并且要么有生理学证据COPD（1秒用力呼气量（FEV1）与用力肺活量比<0。70) 或作为年龄和性别匹配的对照，从不吸烟，肺功能正常（CanCOLD 队列）。由于他们研究中的绝大多数 (83%) 大麻吸烟者也吸烟，因此通过调整双重吸烟者同时使用大麻来进行分析。剂量-反应分析通过使用三个累积终生暴露水平（由吸烟年数或联合年数定义）（轻度，1-5；中度，>5-20；重度，>20）对吸烟者进行分类，并且在分析中调整了暴露水平以及其他有影响的协变量。在他们的横断面研究中，作者发现大量吸食大麻（>20 关节年）与肺活量测定定义的 COPD 相关，而在他们的纵向研究中，发现重度吸食大麻者的 FEV1 年下降速度要快得多（与从不吸烟者相比，接近 30 mL·yr-1），甚至比重度吸烟者中观察到的下降速度还要快（略大于 20 mL·yr−1）。WC Tan 及其同事的报告提出了关于吸食大麻对老年人肺功能影响的重要问题，但未能直接回答这些问题 http://bit.ly/2LP2AYi