to the editor: We would like to commend Drs. Benich and Carek for their thoughtful review of the evaluation of chronic cough. The authors pointed out that cigarette smoke is a major factor to consider as a cough-evoking irritant. We are writing to call attention to another potential irritant that should be considered during a comprehensive evaluation of chronic cough: cannabis smoke.
Cannabis is the most widely used illicit substance in the United States, with 17.4 million past-month users and an estimated 4.6 million persons smoking cannabis on a daily or almost daily basis in 2010.1,2 Many of these persons will be evaluated for various reasons in a primary care setting. For example, a study of 236 consecutive urban primary care patients presenting for routine evaluation found a 5.1 percent prevalence of cannabis use within the past 90 days.3 Because respiratory symptoms, including chronic cough, are among the most common medical consequences of long-term cannabis use,4 primary care physicians may see patients with chronic cough in whom cannabis use is a contributing factor.
Direct inquiry about cannabis use can be integrated with assessment for other potential respiratory irritants. By combining questions about cannabis and tobacco use, the relevant history may be obtained in a nonjudgmental manner. Assessment can also be enhanced by brief, validated screening methods, such as the Alcohol, Smoking, and Substance Involvement Screening Test from the World Health Organization,3 which is recommended by the National Institute on Drug Abuse for use in general medical settings.5 An online version of this tool (available at http://www.drugabuse.gov/nmassist/) guides physicians through a short series of screening questions and generates a substance involvement score that suggests the level of intervention needed.
Chronic cough is an important and common clinical problem. Awareness of the prevalence, consequences, and strategies for identification of long-term cannabis use will equip physicians to be better able to evaluate and treat patients with chronic cough.
editor's note: This letter was sent to the authors of “Evaluation of the Patient with Chronic Cough,” who declined to reply.