One in six patients in primary care reported cannabis use, with 35% of those using at levels indicating moderate- to high-risk for cannabis use disorder, new UCLA research finds.

The findings, published June 5 in JAMA Network Open, suggest that most patients reported using cannabis for symptom management, despite identifying as recreational users, indicating the need for routine cannabis screening. Currently, few health care systems offer this screening in primary care settings.

"Patients may not tell their primary care providers about their cannabis use, and their doctors may not ask about it," said lead author Dr. Lillian Gelberg, professor of family medicine at the David Geffen School of Medicine at UCLA and of health policy and management at the UCLA Fielding School of Public Health. "Not asking patients about their cannabis use results in a missed opportunity for opening up doctor-patient communication regarding use of cannabis generally and for management of their symptoms."

Some 38 states, three US territories and the District of Columbia allow cannabis for medical use, and 24 of these states also permit recreational use. Stigma over cannabis use has fallen likely due to these legal moves. While there has been an increased perception that its use is risk free, cannabis potency has increased.

The U.S. Preventive Services Task Force recommended in 2020 that primary care physicians screen their adult patients for use of cannabis and other substances. The following year, the investigators implemented the UCLA universal electronic health record-based, self-administered survey on cannabis use and medical cannabis use. Patients complete this survey as pre-visit screening prior to their primary care visits as sent to them via the Epic patient portal.

The researchers used patients' de-identified electronic health records at UCLA collected from January 2021 to May 2023 to determine the prevalence, correlates and reasons for current cannabis use. The UCLA Health system is one of the few to ask patients to voluntarily complete cannabis use surveys during pre-appointment check-ins. The survey used the WHO Alcohol Substance Involvement Screening Test (ASSIST) to assess cannabis use.

Nearly 176,000 patients completed surveys. Of those, nearly 30,000 (17%) reported cannabis use, among whom 35% had results suggesting moderate- to high-risk for a cannabis use disorder, defined as a score of 8 or higher on the screening survey. Among users, 40% used cannabis once or twice in the previous three months, 17% used monthly, 25% used weekly and 19% used it daily or almost daily.

Other findings included:

• Cannabis use was lowest among people living in the most disadvantaged neighborhoods (14%), yet the risk for disordered use was highest among this group
• Inhaled modes of cannabis use were as common as ingestion (65.0% and 64.7%), including 29% who vaped
• 47% used cannabis for medical reasons
• 76% used it to manage symptoms such as mental health symptoms or stress (56%), sleep (56%), and pain (37%). Further, most patients who reported using cannabis only for recreational reasons had also used it at some point to manage a symptom.

The study has some limitations. The findings are based on patients' self-reported use and though cannabis is legal in California, some patients may still have been reluctant to disclose using it.

Much of the data were from screenings taken during the COVID-19 lockdown, during which cannabis use may have been higher than it might have been otherwise. In addition, the findings may not be applicable to other health systems, particularly in states where cannabis use is still illegal.

However, "given the high rates of cannabis use and medical cannabis use that we found in this large urban health care system, it is essential that health care systems implement routine screening of all primary care patients," the researchers write.

"Integrating screening efforts to include information regarding cannabis use for symptom management could help enhance the identification and documentation of medical cannabis usage, particularly in the health care context."