Cigarette et "joint" : nuisance comparée.

Évaluation respiratoire de 339 sujets répartis en 4 groupes :

                                fumeurs réguliers
de cannabis
de tabac
des 2 substances
non fumeurs


Résultats :

1 joint = 2,5-5 cigarettes comme inducteur d´obstruction bronchique.

Effects of cannabis on pulmonary structure, function and symptoms

Sarah Aldington1, Mathew Williams1, Mike Nowitz2, Mark Weatherall3, Alison Pritchard1, Amanda McNaughton1, Geoffrey Robinson1, Richard Beasley1
1 Medical Research Institute of New Zealand, Wellington, New Zealand
2 Pacific Radiology, Wakefield Hospital, Wellington, and Wellington School of Medicine and Health Sciences, Wellington, New Zealand
3 Wellington School of Medicine and Health Sciences, Wellington, New Zealand

Correspondence to:
Professor Richard Beasley, Medical Research Institute of New Zealand, P O Box 10055, Wellington 6143, New Zealand; Richard.Beasley@mrinz.ac.nz

Background: Cannabis is the most widely used illegal drug worldwide. Long-term use of cannabis is known to cause chronic bronchitis and airflow obstruction, but the prevalence of macroscopic emphysema, the dose-response relationship and the dose equivalence of cannabis with tobacco has not been determined.

Methods: A convenience sample of adults from the Greater Wellington region was recruited into four smoking groups: cannabis only, tobacco only, combined cannabis and tobacco and non-smokers of either substance. Their respiratory status was assessed using high-resolution CT (HRCT) scanning, pulmonary function tests and a respiratory and smoking questionnaire. Associations between respiratory status and cannabis use were examined by analysis of covariance and logistic regression.

Results: 339 subjects were recruited into the four groups. A dose-response relationship was found between cannabis smoking and reduced forced expiratory volume in 1 s to forced vital capacity ratio and specific airways conductance, and increased total lung capacity. For measures of airflow obstruction, one cannabis joint had a similar effect to 2.5–5 tobacco cigarettes. Cannabis smoking was associated with decreased lung density on HRCT scans. Macroscopic emphysema was detected in 1/75 (1.3%), 15/92 (16.3%), 17/91 (18.9%) and 0/81 subjects in the cannabis only, combined cannabis and tobacco, tobacco alone and non-smoking groups, respectively.

Conclusions: Smoking cannabis was associated with a dose-related impairment of large airways function resulting in airflow obstruction and hyperinflation. In contrast, cannabis smoking was seldom associated with macroscopic emphysema. The 1:2.5–5 dose equivalence bet