Screening and managing cannabis use: comparing GP’s and nurses’ knowledge, beliefs, and behavior
© Norberg et al.; licensee BioMed Central Ltd. 2012
Received: 5 June 2012
Accepted: 10 July 2012
Published: 24 July 2012
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© Norberg et al.; licensee BioMed Central Ltd. 2012
Received: 5 June 2012
Accepted: 10 July 2012
Published: 24 July 2012
General practitioners (GPs) and nurses are ideally placed to address the significant unmet demand for the treatment of cannabis-related problems given the numbers of people who regularly seek their care. The aim of this study was to evaluate differences between GPs and nurses’ perceived knowledge, beliefs, and behaviors toward cannabis use and its screening and management.
This study involved 161 nurses and 503 GPs who completed a survey distributed via conference satchels to delegates of Healthed seminars focused on topics relevant to women and children’s health. Differences between GPs and nurses were analyzed using χ2- tests and two-sample t-tests, while logistic regression examined predictors of service provision.
GPs were more likely than nurses to have engaged in cannabis-related service provision, but also more frequently reported barriers related to time, interest, and having more important issues to address. Nurses reported less knowledge, skills, and role legitimacy. Perceived screening skills predicted screening and referral to alcohol and other drug (AOD) services, while knowing a regular user increased the likelihood of referrals only.
Approaches to increase cannabis-related screening and intervention may be improved by involving nurses, and by leveraging the relationship between nurses and doctors, in primary care.
Cannabis remains the most commonly used illicit drug, with around 200 million current users worldwide . Cannabis use increases the risk of chronic respiratory and cardiovascular problems [2–5], and around one in nine users are at risk of developing dependence [6, 7]. In Australia, these health risks are of significant concern given that cannabis use contributes to 10% of the burden relating to illicit drug use . While few cannabis users seek specialist drug treatment [9, 10], general practitioners (GPs) are the most frequently sought resource for treatment of cannabis use . As approximately 80% of Australians visit a GP at least once a year , primary care provides substantial opportunity for cannabis use screening and intervention. Doctors and nurses in primary care may be able to influence their patients’ cannabis use through a variety of health strategies , but their attitudes, knowledge, and skills may limit the provision of such care [14, 15].
Although primary care practitioners are encouraged to, and typically believe it is appropriate for them to screen and provide early interventions for substance use , many do not feel comfortable diagnosing or treating substance use problems [17–19]. Further, the content of a typical substance use brief intervention is not well known  and commonly disregarded as ineffective [18, 20]. Many doctors and nurses have reported avoiding substance use discussions due to anticipated negative reactions from patients, believing that patients will not be honest about their substance use, not having enough training and resources, and time constraints [18, 20–22]. Conversely, doctors and nurses report that having readily available support services, quick and easy screening instruments and counseling material, more training, and evidence of the successful impact for early intervention would lead to their greater involvement in screening and intervention [16, 20, 22].
If more cannabis screening and intervention were to occur within primary care, a key question is whether nurses or GPs could more feasibly undertake this work. While nurses may be less subject to the time constraints for opportunistic intervention that doctors experience [23, 24], findings from the alcohol literature indicate that nurses compared to GPs have less knowledge and skills about screening and intervention [16, 25], have less favorable attitudes towards discussing substance use with their patients , and are less likely to believe that this work should be a part of their role . In addition, qualitative research found that nurses can be hesitant to provide alcohol interventions because of their own use and enjoyment of alcohol and because of their beliefs that alcohol use may serve beneficial social and coping functions for some patients . If these alcohol-related findings are transferrable to cannabis use, they suggest that nurses may be less inclined than GPs to screen for cannabis use and provide early intervention.
While a modest amount of research has examined GP’s and nurses’ attitudes towards alcohol and substance use in general, relatively little has focused specifically on cannabis use. In a UK survey of 97 GPs, most believed that cannabis use posed a health risk and may lead to mental health problems, but less than half believed that they had adequate knowledge about cannabis use, and only a third felt confident in their ability to advise patients about their cannabis use . In addition, around half believed that GPs should refer patients with cannabis-related problems to specialist drug services, with only a third believing it was appropriate to treat cannabis dependence in primary care. GPs who believed it was appropriate to treat cannabis dependence in primary care felt more confident in their ability to advise cannabis-using patients, whereas GPs who believed cannabis-using patients should be referred to specialist drug services reported a greater need to improve their knowledge of cannabis-related risks.
The aim of this study was to assess potential differences between GPs and nurses. Based on findings reviewed above, we hypothesized that while few GPs and nurses would be confident in their knowledge and skills about cannabis use and its treatment, nurses would report having less training (Hypothesis 1) and less role legitimacy for screening and treating cannabis use (Hypothesis 2), and perceive their knowledge and skills to be poorer than GPs (Hypothesis 3). In addition, we hypothesized that GP’s and nurses’ training, personal experience, knowledge, attitudes, and beliefs would be related to whether or not they engaged in screening or intervention for cannabis use (Hypothesis 4).
The study sample was comprised of delegates attending a Healthed seminar in one of five Australian cities (Sydney, Melbourne, Adelaide, Brisbane, and Perth) in 2011. Each Healthed seminar featured approximately sixteen lectures on women and children’s health and represented a rare opportunity to meet with several hundred GPs and nurses in one location. GPs and nurses received professional education points for attending the lectures. Of the 1,925 delegates who attended the Healthed seminars, 664 (35%) completed the study survey; 503 surveys were completed by GPs (76%) and 162 were completed by nurses (24%). This distribution was representative of the Healthed population, in which 71% were GPs and 26% were nurses. The study sample was predominately female (n = 527, 79%), which again reflects the Healthed population, as only 41% of Australian GPs are female . The sample had a mean age of 48 years (SD = 9.88, range 21-81) and most practiced in a metropolitan area (n = 463, 71%). GPs were significantly more likely to be male (27% vs. <1%; χ2(1) = 51.23, p < 0.001), and younger (GPs M age = 47.61 years, SD = 10.25; nurse’s M age = 49.93 years, SD = 8.04; t(343.77) = -2.95, p = 0.003), and reported spending significantly more hours in the clinic per week than did nurses (GP M hours = 30.45, SD = 12.65; nurse’s M hours = 26.56, SD = 12.04; t(646) = 3.35, p = 0.001.
During the opening of each Healthed seminar, we informed delegates that the survey and its information and consent form were located in their conference satchel. We advised delegates that if they were interested in participating that they should complete the entire self-report survey, as item nonresponse would render their survey invalid given the brevity of the survey. We instructed delegates to turn in their surveys, before afternoon tea, into dropboxes at the conference. Lastly, we instructed delegates that participation would result in entry into a lottery held during afternoon tea to win one of five gift certificates ($75 AUD). These procedures reflect a cross-sectional design.
The survey was devised primarily for use in this study, and thus, had not been psychometrically validated. The survey had 31 items; of which 25 were relevant to the current study. Five items addressed basic demographic information (career, gender, age, physical location of practice, and weekly clinical hours), and two items covered exposure to cannabis issues (relevant training and personal experience with a regular cannabis user). Five items assessed knowledge regarding cannabis use (e.g., Cannabis users are more likely to have a mental health problem than those who do not use cannabis); four of these items were rated on a Likert scale from 0 (disagree completely) to 4 (agree completely). The fifth knowledge item was answered with a percentage (What percentage of people who try cannabis will someday develop cannabis dependence?).
The remaining 13 items used in this study were based on previous surveys assessing health practitioners’ beliefs, attitudes, and behavior regarding substance use and its treatment. Three items required GPs and nurses to assess their own knowledge about cannabis use and their skills related to screening and managing cannabis use [16–18, 27]. These three items were rated on a Likert scale from 0 (very poor) to 4 (very strong). In addition, three items assessed beliefs regarding role legitimacy—factors related to the appropriateness of a GP or nurse to intervene with someone’s cannabis use [21, 25, 27, 28] and were rated on a Likert scale from 0 (disagree completely) to 4 (agree completely). One item assessed attitudes regarding cannabis use policy (Cannabis use should be illegal / decriminalized / available for medical use) [22, 29]. Four open-ended items assessed behavior related to screening, intervention, and referral [22, 28, 30]. Participants responded to these items with numbers (e.g., I have screened ____ patients for cannabis use in the last month). The final two items assessed barriers and facilitators to screening and treatment provision [18, 20, 25, 27–29]. These items were answered by checking all applicable barriers or facilitators. Options referred to attitudes, motivation, confidence, and support.
Differences between GPs and nurses on categorical variables were analyzed using 2 Χ 2 χ2- tests (e.g., Hypothesis 1), while two-sample t-tests were used for continuous variables (e.g., Hypothesis 2, Hypothesis 3). When Levene’s test for equality of variances indicated that the variances between GPs and nurses responses were significantly different, a two-sample t-test was performed that did not assume equal variances. Logistic regressions using a generalized linear function examined the prediction of service provision (Hypothesis 4; 0 = none, 1 = at least once; reference category = 0). Before conducting the logistic regressions, zero-order correlations were conducted to determine which variables were appropriate for model inclusion. Only items statistically significant at the univariate level were included at the multivariate level. The significance level for all statistical tests was set at p < 0.01 to reduce Type I errors associated with multiple testing.
Exposure to Cannabis Use
Cannabis Related Training
Cannabis users known to participantsa
Relative (other than child)
Knowledge and Beliefs about Cannabis Use and its Treatment
Cannabis users are more likely to have a mental health problem than those who do not use cannabis
GPs (N = 502)
Nurses (N = 160)
Effective psychological treatments exist for helping people to reduce their cannabis use
GPs (N = 501)
Nurses (N = 159)
Effective pharmacological treatments exist for assisting with cannabis withdrawal
GPs (N = 499)
Nurses (N = 159)
Withdrawal can be a barrier to quitting cannabis
GPs (N = 500)
Nurses (N = 158)
Conducting a 10 minute brief assessment of someone’s cannabis use can lead to reductions in their use
GPs (N = 501)
Nurses (N = 159)
People in my position are effective in treating patients with cannabis use problems
GPs (N = 499)
Nurses (N = 160)
People in my position should receive education about cannabis
GPs (N = 501)
Nurses (N = 160)
On average, GPs believed that 21% (SD = 21.58) of people who try cannabis will someday develop cannabis dependence, which was significantly less than nurses believed (M = 25%, SD = 21.58), t(131.51) = -1.14, p = 0.001. Of the 516 participants who responded to this item, only 24% (n = 126) responded with an estimate close to 9% (6-12%) [6, 7]. Twenty-one percent of participants did not answer the question.
Nurses reported significantly less role legitimacy about providing cannabis-related services. Compared to nurses, GPs more strongly agreed that conducting a 10-minute brief assessment of someone’s cannabis use can lead to reductions in cannabis use (p < 0.001) and that people in their position are effective in treating patients with cannabis use problems (p < 0.001). Almost all GPs and nurses agreed that people in their position should receive education regarding cannabis (See Table 2).
Self-Assessment of Knowledge about Cannabis Use and Skills Related to Screening and Managing Cannabis Use
Knowledge about Cannabis
GPs (N = 501)
Nurses (N = 159)
Skills in Screening for Cannabis Use
GPs (N = 499)
Nurses (N = 157)
Skills in Managing Cannabis Use
GPs (N = 495)
Nurses (N = 156)
In the previous month, GPs reported screening an average of 3.84 (SD = 7.82, n = 498) patients for cannabis use and treating an average of 1.71 (SD = 4.17, n = 500) patients for cannabis use; although, approximately half (46%, n = 230) had not engaged in any screening or intervention provision (51%, n = 254). Nurses reported screening an average of 2.22 (SD = 10.00, n = 158) patients for cannabis use and treating an average of 1.33 (SD = 8.40, n = 159) patients for cannabis use in the last month. Most nurses, however, had not screened (85%, n = 134) or provided an intervention to any patients for cannabis use (87%, n = 139). In addition, GPs and nurses had referred less than one patient in the last month to an alcohol and other drug (AOD) facility (GPs: M = 0.48, SD = 1.42, n = 500, 374 (75%) had not engaged in referral; Nurses: M = 0.84, SD = 4.62, n = 160, 139 (87%) had not engaged in referral) or to a mental health service (GPs: M = 0.76, SD = 1.78, n = 500, 318 (64%) had not engaged in referral; Nurses: M = 0.44, SD = 2.39, n = 160, 143 (89%) had not engaged in referral). GPs were statistically significantly more likely to have engaged in screening (χ2(1) = 72.45, p < 0.001), treatment (χ2(1) = 64.85, p < 0.001), and referral (AOD: χ2(1) = 10.21, p = 0.001; Mental Health: χ2(1) = 38.24, p < 0.001) at least once (versus not at all) compared to nurses.
Binary Logistic Regressions Estimating Screening, Intervention, and Referral Provision in the Previous Month
Referral to AOD Services
Referral to Mental Health Services
Cannabis Should not be Illegalb
Cannabis Should not be Decriminalizedb
Cannabis Should not be Available for Medicinal Purposesb
No Regular User Friendc
Perceived Screening Skills
Perceived Management Skills
10 Minute Brief Assessment Can Reduce Use
Effective Psychological Treatments Exist
People in My Position Are Effective
Confidence in the provision of screening was important, with every unit increase in perceived screening skills associated with a 3.28 times greater chance of having engaged in screening provision in the previous month and an 8.69 times greater chance of having referred a patient to an AOD service. Neither the degree of training, knowledge, nor perceived skills in cannabis intervention, however, offered a significant unique prediction of screening, intervention, or referral.
Health professionals who had a friend who regularly used cannabis were 1.80 to 1.83 times more likely to have referred someone to an AOD or mental health service than those without such a friend. In regards to attitudes, participants who believed cannabis should not be available for medicinal purposes were 2.06 times more likely to screen for cannabis use than those who believed it should be available. While that attitude was a significant univariate correlate of intervention and referral to a mental health service, it did not provide a unique prediction of those actions.
Barriers and Facilitators for Cannabis Use Screening and Intervention ( N = 664)
GPs agreement n(%)
Nurses agreement n(%)
Do not have the skills to screen or provide an intervention
Cannabis use often is not the most important issue that needs to be addressed during a patient’s visit
Patients may not be receptive to screening or intervention
Do not have time to screen or provide an intervention
Do not have support from colleagues/organization to screen or provide an intervention
The effort required to motivate a cannabis user to quit is not justified by the likelihood of a positive outcome
Do not have a personal interest in providing screening or treatment for cannabis use
Do not have professional interest in providing screening or treatment for cannabis use
I do not want to attract more cannabis users to my clinic
Most people who use cannabis do not need screening or treatment
Cannabis users are unpleasant to work with
Cannabis users should only be treated by specialists in the field
Access to up-to-date management guidelines and recommendations
Having more options for referrals
Having more resources to assist me (e.g., web interventions)
Believing that screening and intervention would lead to positive outcomes
Believing that screening and intervention are clinically important
Nothing would facilitate the screening or intervention of cannabis use
This study evaluated GP’s and nurses’ perceived knowledge, beliefs, and behaviors toward cannabis use and its screening and management. As a whole, the findings suggest that despite GPs and nurses having little to no training in cannabis-related issues, most are aware of basic treatment-related issues and believe that it is part of their role to be educated about cannabis use. Yet, many GPs and nurses believed their knowledge about cannabis use and their skills in screening and managing cannabis use to be poor. The findings also suggest that nurses may be less knowledgeable about cannabis use and feel less role legitimacy for its screening and treatment. Thus, it is not surprising that being a GP was consistently associated with cannabis service provision compared with being a nurse. When controlling for other relevant variables, GPs were three to five times more likely than nurses to have engaged in screening, brief intervention, and referral to mental health services. Study findings also indicate that policy attitudes, personal experience, and perceived screening skills may influence service provision.
The finding that nurses perceive themselves to be less knowledgeable and to have less role legitimacy than GPs is consistent with alcohol use research [16, 25]. While GPs rated their knowledge and skills better than did nurses, it is important to note that less than half of GPs considered their knowledge and screening skills to be acceptable to very strong and less than one-third considered their skills in managing cannabis use to be acceptable to very strong. In addition, only a quarter of GPs and nurses reported an accurate estimate of the chance of developing dependence [6, 7]. As 21% of participants did not answer the question, 24% may overestimate the actual rate of accurate responses, as those who did not know the accurate figure may have chosen to skip this item. Both GPs and nurses also overestimated the effectiveness of pharmacological treatments . These findings indicate that even though nurses may benefit from training in cannabis-related issues more so than GPs, training also has the potential to improve GP’s service provision to cannabis users.
Consistent with previous research [18, 20–22], GPs and nurses identified not having enough skills, patients not being receptive, and not having enough time as common reasons for not engaging in screening and intervention for cannabis use. Not believing that cannabis use is the most important issue was a new common barrier identified in this study. Given that more GPs than nurses endorsed this barrier, it is not surprising that GPs were more likely than nurses to report not having enough time and that having more referral options would facilitate their service provision. These findings suggest that GPs may see more legitimacy for their role in screening than they do intervention provision. As this study did not examine health practitioners’ beliefs about their role legitimacy for screening, future research would benefit from examining role legitimacy beliefs for both screening and intervention provision.
Prior to this study, scant research had statistically examined whether personal views and experience with cannabis use influenced service provision. An exception is Johnson and colleagues’ study , which found that primary care physicians who had family and friends with substance use problems had less difficulty discussing substance use with patients. The current study found that having a friend who regularly uses cannabis increased referral provision, but not screening and intervention provision. This study also identified that compared to health practitioners who believed that cannabis should be available for medicinal purposes, those who believed cannabis should not be available for medicinal purposes were twice as likely to have screened a patient for cannabis use. Along with Lock and colleagues’  finding that nurses’ beliefs about alcohol’s perceived benefits affect their willingness to provide alcohol-related services, these findings suggest that training in cannabis-related issues should incorporate discussions on the effectiveness of cannabis for medicinal purposes and how personal experience can shape their professional behavior. Doing so may help to motivate all health practitioners to engage in evidenced-based service provision.
General practitioners and nurses represent the overwhelming majority of primary care providers in Australia. They have enormous potential to reach a broad range of people for early intervention, where the focus is on prevention and health promotion. Although Australian GPs are being encouraged via government reimbursement schemes to provide brief advice in many prevention areas, including drug and alcohol use , efforts to increase service provision for cannabis users may need to be directed at both nurses and GPs, in order to utilize the opportunity for collaboration between GPs and nurses in the primary care setting. There are several reasons why nurses should be involved in this process. First, nurses were consistently less likely to have engaged in service provision than GPs. Second, GPs in this study were substantially more likely to identify barriers to service provision that are difficult to resolve, such as not having enough time and cannabis use not being the most important issue. Third, in 2010 the Australian Government announced a $523 million investment in Australia’s nurses in order reduce GP’s clinical burden . Such an investment increases the need to improve nurses’ skills to ensure that they are fully able to undertake effective preventive health activities. Although the aim of the initiative is to allow GPs to focus on diagnosis, while nurses focus on tasks such as care co-ordination, health assessments, and health education , the most suitable model of practice for nurses has not been established. Thus, when developing training models, researchers will need to keep in mind that nurses may be operating from a substitution model (only doing those tasks delegated to them) or from a collaborative model (working autonomously within a practice). In addition, researchers will need to find an effective method for resolving the low legitimacy that nurses feel for managing cannabis use.
Hence, part of a training strategy may require education and empowerment of nurses in terms of their clinical potential to assist in managing cannabis use problems. In a substitution model, it may be advantageous to educate both GPs and nurses in how best to utilize their respective clinical strengths. This might involve nurses performing the screening and assessment of patients’ readiness for change and then referring motivated patients on to GPs for a brief intervention. GPs may develop clinical plans that involve utilizing nurses in their role as health educators. This would allow GPs to remain in the referral process, but minimize their clinical burden, while appropriately managing patients concerns. In those circumstances where nurses and nurse practitioners are working in a relatively autonomous context, nurses could be trained in both screening and intervention, referring to the GP only when the extremity of clinical features might warrant it.
Regardless of whom efforts are focused on, combining motivational interviewing with screening and intervention training for cannabis use may lead to greater provision of services to individuals who use cannabis. Research has found that motivating GPs to provide an intervention does not need to involve long professional development sessions. For example, a 20-minute motivational discussion with GPs has substantially increased their likelihood of discussing methods for managing dependent cannabis users . Such motivational training may circumvent the negative effect that health practitioners’ pre-existing low motivation has on service provision. Providing GPs with training and support has been found to only increase provision of alcohol screening and brief advice for those GPs who were already motivated to work with patients with alcohol problems prior to receiving training . Almost all GPs and nurses in the current study reported it was part of their role to receive education about cannabis use, and over three-fourths reported that receiving more training would increased their service provision. As such, providing training in screening (that includes information about screening resources, practice guidelines, and referral options) and in brief motivational interventions (that includes information about treatment resources, and discussion of personal experience and medicinal cannabis use) during professional development seminars may increase service provision for cannabis users.
When evaluating the effects of training on GPs’ and nurses’ service provision, researchers should carefully monitor increases in knowledge and attitudes toward service provision. Previous research found that training in a brief intervention led to increases in the understanding of a brief intervention for nurses, but not GPs . Furthermore, while nurses’ knowledge about alcohol increased as a result of training, their positive attitudes towards discussing alcohol with patients decreased. Thus, training needs to be carefully developed and administered to avoid potential negative consequences.
The strength of the study is its large sample size. Limitations include the sole recruitment of health practitioners from Healthed seminars, reliance on self-reports of service provision, using a survey without established psychometric properties, and the low response rate (35%). Notably, the obtained survey response rate was similar to other surveys conducted with Australian GPs [34, 35], and thus, may not be indicative of non-respondents being less interested in cannabis use than responders. An additional limitation of this study is the high amount of missing data regarding the percentage of patients who will develop dependence (21% missing data). Research suggests that the high nonresponse on this item may have been due to the cognitively demanding nature of the question . In order to reduce the non-response rate for this item, future researchers may want to adapt the open-ended item to include response options. Lastly, respondents were not provided with operational definitions for screening, brief interventions, or referrals; therefore, these items may have been interpreted differently. In light of these limitations, results may only generalize to GPs and nurses interested in women’s and children’s health who also have an interest in contributing to research. Future research with professionals interested in men’s health and that uses operational definitions and a validated survey may obtain different results.
This study found that as a group, GPs and nurses perceive their knowledge and skills pertaining to cannabis-related issues to be poor. In addition, this study identified that health professionals’ occupation, attitudes, personal experience, and skills may affect their provision of cannabis-related care. Education and training, therefore, may be particularly important to improving service provision for individuals who use cannabis, especially training that utilizes the complementary roles that each professional plays in general practice, with a special emphasis on increasing nurses’ knowledge, skills, and role legitimacy.
MMN is a clinical psychologist and senior lecturer. PG is a doctoral student in Community Medicine and Public Health. PD is a drug and alcohol educator. DJK is a clinical psychologist and professor. RM is a general practitioner and senior lecturer. JC is a professor who has a PhD in Community Medicine and Public Health.
This work was carried out at the National Cannabis Prevention and Information Centre at the University of New South Wales. All surveys were distributed during HealthEd seminars conducted in major cities across Australia.
The authors gratefully acknowledge the Department of Health and Aging (DoHA) for providing funding for the National Cannabis Prevention and Information Centre, and subsequently, the present study. DoHA had no role in study design or in the decision to submit the study for publication. DoHA also had no role in the collection, analysis and interpretation of data in the writing of the manuscript. The authors also acknowledge Ms Morag Millington, Julia Tropiano, and Lucy Albertella for their assistance with data collection and data entry. Early findings from this study were presented at the 2011 Australasian Professional Society on Alcohol and other Drugs Conference.
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