In Washington State primary care clinics, 15.3% of patients reported past-year cannabis use and 3.1% used daily, with rates reaching 36% among 18-29 year olds and 32% among young men who smoked tobacco.
Read this if you live in a state where cannabis is legal and want to know how common use is among people visiting their doctors.
31.7% of young adults with depression reported daily cannabis use
What the researchers found
This study analyzed cannabis use screening results from 22,095 primary care patients in Washington State, one of the first states to legalize recreational cannabis.
Overall, 15.3% reported any past-year cannabis use and 3.1% reported daily use. These rates were substantially higher than national averages at the time.
Age was the strongest predictor: 36% of patients aged 18-29 reported any cannabis use and 8.1% reported daily use. Among the youngest patients, behavioral health factors dramatically increased daily use rates. Young men aged 18-29 who also used tobacco had a 25.5% daily cannabis use rate, and those who screened positive for depression had a 31.7% daily use rate.
The study demonstrated the feasibility of routine cannabis screening in primary care, with 74% of eligible patients completing the screening question.
Why it matters
This is one of the first large-scale assessments of cannabis use among primary care patients in a legalized state. The high rates among young adults with behavioral health conditions highlight the need for integrated screening and intervention in primary care settings.
The numbers in context
22,095 patients screened (74% completion). 15.3% any past-year use. 3.1% daily use. Ages 18-29: 36% any use, 8.1% daily. Young men with tobacco use: 25.5% daily cannabis use. Young patients with depression: 31.7% daily cannabis use.
How the study worked
Observational cohort study of 29,857 adults visiting primary care clinics with annual behavioral health screening (March 2015 to February 2016). Cannabis use was assessed with a single-item frequency question. Depression, alcohol, and other drug use were also screened. Electronic health records provided tobacco use and behavioral health diagnoses.
What this study cannot tell us
Single-item screening may miss nuances of use patterns. Patients seen in one health system in Washington State may not represent other populations. The study occurred shortly after recreational legalization, and patterns may have changed since. The 26% who did not complete screening may differ systematically from completers.
How to read the evidence
Large observational study with validated screening in real-world clinical settings. Moderate because it provides strong descriptive data but cannot establish causation.
When this study was published
Published in 2017, with data from March 2015 to February 2016.
The bigger picture
As more states legalize cannabis, primary care settings become a critical point for identifying problematic use. This study provides a model for integrating cannabis screening into routine behavioral health assessment and identifies the patient subgroups most in need of attention.
Questions still open
- Has daily cannabis use increased further in Washington State since 2016? Do primary care patients who use cannabis daily benefit from brief interventions? Should cannabis screening trigger different clinical responses depending on the patient's age and mental health status?
Common questions
How common is cannabis use among doctor's patients?
Is cannabis use linked to depression?
Read the original research
Frequency of Cannabis Use Among Primary Care Patients in Washington State.
Journal of the American Board of Family Medicine : JABFM, 30(6), 795-805
Citation
Lapham, Gwen T; Lee, Amy K; Caldeiro, Ryan M; McCarty, Dennis; Browne, Kendall C; Walker, Denise D; Kivlahan, Daniel R; Bradley, Katharine A. (2017). Frequency of Cannabis Use Among Primary Care Patients in Washington State.. Journal of the American Board of Family Medicine : JABFM, 30(6), 795-805. https://doi.org/10.3122/jabfm.2017.06.170062
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