Results suggest that ED patients who use drugs other than cannabis are at particular risk for high drug use severity and concomitant problems such as psychiatric problems and alcohol use severity. However, 19–29% of cannabis-only users were identified as having problematic drug use. Furthermore, daily cannabis-only users fared less well than nondaily cannabis users with regard to drug use severity indicators and self-efficacy for avoiding drug use, even though they were younger as a group.

Although cannabis may be less harmful to individual health relative to other forms of drug use, heavier cannabis use is a concern because it may be associated with mental and physical health problems.^7–10,20 Cannabis dependence does occur, and individuals often perceive themselves as unable to stop.²¹ Daily cannabis-only users in our study were found to have particularly low confidence in avoiding drug use (compared with nondaily cannabis users and even other drug users). However, there is a distinction between self-efficacy and motivation, perceived importance, and desire to avoid drug use—daily cannabis users may not be motivated or see the importance of avoiding use. Connor et al.²² found low cannabis refusal self-efficacy was related to problematic use. Enhancement of motivation and self-efficacy beliefs could be an important target of prevention and treatment. As with other drug use, behavioral interventions and motivational enhancement appear to be useful with problematic cannabis use.²¹ Screening, brief intervention, and referral to treatment (SBIRT) is a promising public health strategy that has been implemented in EDs to reduce risks associated with substance use.^23–25 Although SBIRT has been shown to be effective for alcohol misuse, its impact on drug use, including cannabis, is less conclusive. However, SBIRT's emphasis on motivation and harm reduction could fit well with cannabis use reduction goals to the degree that many cannabis users express interest in reducing use rather than abstinence.²¹

Possible limitations of the study include not having information about the reason for the ED visit and uncertainty of the degree to which respondents are representative of the overall ED population. Use of cannabis in terms of medical or recreational use was not analyzed, an important distinction since there is some evidence that medical and recreational cannabis users differ in their clinical characteristics.²⁶ The quantity used and the frequency of use per day were not collected. In addition, reliance on self-reports may have resulted in underestimates of cannabis use and other drug use.

Across the drug use groups, 45% of the ED participants screened positive for problematic drug use, a percentage that varied considerably by type of drug (cannabis vs. other) and frequency of use (daily vs. nondaily). This information may assist emergency medicine providers and social work professionals in matching patients to appropriate intervention. For example, users of drugs other than cannabis (and perhaps heavy, chronic cannabis users) may need referral to specialty services for further assessment. Recently, Konstantopoulos et al.⁵ suggested a clinical decision rule for performing a detailed assessment of ED patients for possible problematic drug use that is based on the type of drug. Because the ED represents an important “opportunistic” venue for harm reduction and intervention efforts with drug users, hospital staff and health educators screening for substance use should be attentive to differences in use patterns among patients, as some adverse consequences may depend on the type and frequency of substances being used.