Discover Portal

Smoking cannabis

NIHR Signal Voucher rewards do not reduce frequency of cannabis use or relapse in people with early psychosis

Published on 19 December 2019

doi: 10.3310/signal-000836

Contingency management - the use of positive reinforcement in the form of supermarket vouchers to shape behaviour - makes no difference in the frequency of cannabis use or relapse rates in those with early psychosis. Although psychotic symptoms initially decrease, these changes are not sustained over the longer term and are no better than with an optimised educational intervention.

This NIHR-funded multicentre randomised controlled trial included 551 young adults who were being treated in an ‘Early Intervention in Psychosis’ service of 23 NHS trusts in the Midlands and south-east of England. It found no clinical difference in time to relapse, frequency of cannabis use, symptom severity, or engagement in education or work. The total cost of inpatient hospital admissions was slightly lower for those receiving contingency management, but the reason for this is not clear.

Share your views on the research.

Why was this study needed?

Psychosis is a mental health condition that causes people to perceive or interpret things differently from those around them. Psychosis may involve hallucinations or delusions. The use of cannabis, particularly high-potency cannabis, significantly increases the likelihood of psychotic disorder compared with never users. Cannabis was the most commonly used drug in England and Wales in 2017/18. About 2.4 million adults (16 to 59 years) used it that year, including around one million young adults from 16 to 24 years old.

Contingency management, a set of techniques used to reinforce certain behaviours, has proven clinically effective and cost-effective in a variety of contexts including severe mental illness, smoking and alcohol misuse. Most contingency management research has been undertaken in the US.

This trial aimed to examine the impact of a shopping voucher reward contingency management programme on cannabis use and relapse in those with early psychosis to see if it could work in England.

What did this study do?

This trial randomised 511 people aged 18 to 36 to either a combined voucher reward contingency management and optimised psychoeducational intervention or the psychoeducation intervention alone. Contingency management rewarded self-reported abstinence from cannabis use, confirmed by urine analysis, with shopping vouchers. Vouchers began at £5 and rose by £5 every two weeks of abstinence to a maximum of £240 over 12 weeks.

The optimised psychoeducational intervention was six 30-minute sessions on the potential advantages and disadvantages of cannabis use and abstinence. Interviews, questionnaires and electronic patient records were used to determine relapse rates and background data.

A high proportion of participants did not engage in either the contingency management or psychoeducation sessions (they declined or discontinued the intervention). This lack of retention might have reduced the chance of finding a difference if one existed.

What did it find?

  • Similar numbers of participants receiving the psychoeducation sessions (61%) and in the contingency arm (57%) had cannabis-positive urine at 18 months (OR 0.84, 95% CI 0.49 to 1.41). Self-reported cannabis-using days at three months and 18 months were also similar.
  • Clinical outcomes were similar for readmission rate: time to admission (hazard ratio [HR] 1.03, 95% CI 0.76 to 1.40); or likelihood of at least one admission (OR 1.02, 95% CI 0.70 to 1.48).
  • No variance was found in the likelihood of participant engagement in work (OR 0.95, 95% CI 0.62 to 1.46) or study (OR 0.82, 95% CI 0.50 to 1.35).
  • There were mixed results for Early Intervention in Psychosis service users receiving contingency management, with lower rates of positive symptoms at three months (coefficient –0.07, 95% CI –14 to 0) but not at 18 months (coefficient –0.04, CI –0.13 to 0.05).

What does current guidance say on this issue?

The NICE 2017 guideline on drug misuse prevention advocates targeted interventions for people at risk of drug misuse. The NICE 2007 guideline on drug misuse in over 16s advocates a nationwide training programme for NHS staff in contingency management. This guideline reports that the lack of training coupled with staff, service user and public concerns about the longevity of any behavioural change, and the possibility of an intervention appearing to reward drug use, makes the introduction of contingency management in drug misuse services a challenge.

What are the implications?

Contingency management, using the current value of shopping vouchers, is not effective in reducing cannabis use or relapse in people with early psychosis.

The researchers thought that modifying the contingency management programme design or reward level may produce different outcomes. On a positive note, the number of days of cannabis use had reduced in both groups by six months which may indicate that the psychoeducation sessions were beneficial, and they suggest that this is worth exploring further.

Citation and Funding

Johnson S, Rains LS, Marwaha S et al. A contingency management intervention to reduce cannabis use and time to relapse in early psychosis: the CIRCLE RCT. Health Technol Assess. 2019;23(45).

This project was funded by the NIHR Health Technology Assessment Programme (project number 09/144/50).

Bibliography

NHS website. Overview: psychosis. London: Department of Health and Social Care; reviewed 2016.

NICE. Drug misuse in over 16s: psychosocial interventions. CG51. London: National Institute for Health and Care Excellence; 2007, checked July 2016.

NICE. Drug misuse prevention: targeted interventions. NG64. London: National Institute for Health and Care Excellence; February 2017.

Office for National Statistics. Drug misuse: findings from the 2017/18 Crime Survey for England and Wales. Statistical Bulletin 14/18. London: Office for National Statistics; 2018.

Rash CJ, Alessi SM, Zajac K. Examining implementation of contingency management in real-world settings. Psychol Addict Behav; 2019; doi: 10.1037/adb0000496. [Epub ahead of print].

Why was this study needed?

Psychosis is a mental health condition that causes people to perceive or interpret things differently from those around them. Psychosis may involve hallucinations or delusions. The use of cannabis, particularly high-potency cannabis, significantly increases the likelihood of psychotic disorder compared with never users. Cannabis was the most commonly used drug in England and Wales in 2017/18. About 2.4 million adults (16 to 59 years) used it that year, including around one million young adults from 16 to 24 years old.

Contingency management, a set of techniques used to reinforce certain behaviours, has proven clinically effective and cost-effective in a variety of contexts including severe mental illness, smoking and alcohol misuse. Most contingency management research has been undertaken in the US.

This trial aimed to examine the impact of a shopping voucher reward contingency management programme on cannabis use and relapse in those with early psychosis to see if it could work in England.

What did this study do?

This trial randomised 511 people aged 18 to 36 to either a combined voucher reward contingency management and optimised psychoeducational intervention or the psychoeducation intervention alone. Contingency management rewarded self-reported abstinence from cannabis use, confirmed by urine analysis, with shopping vouchers. Vouchers began at £5 and rose by £5 every two weeks of abstinence to a maximum of £240 over 12 weeks.

The optimised psychoeducational intervention was six 30-minute sessions on the potential advantages and disadvantages of cannabis use and abstinence. Interviews, questionnaires and electronic patient records were used to determine relapse rates and background data.

A high proportion of participants did not engage in either the contingency management or psychoeducation sessions (they declined or discontinued the intervention). This lack of retention might have reduced the chance of finding a difference if one existed.

What did it find?

  • Similar numbers of participants receiving the psychoeducation sessions (61%) and in the contingency arm (57%) had cannabis-positive urine at 18 months (OR 0.84, 95% CI 0.49 to 1.41). Self-reported cannabis-using days at three months and 18 months were also similar.
  • Clinical outcomes were similar for readmission rate: time to admission (hazard ratio [HR] 1.03, 95% CI 0.76 to 1.40); or likelihood of at least one admission (OR 1.02, 95% CI 0.70 to 1.48).
  • No variance was found in the likelihood of participant engagement in work (OR 0.95, 95% CI 0.62 to 1.46) or study (OR 0.82, 95% CI 0.50 to 1.35).
  • There were mixed results for Early Intervention in Psychosis service users receiving contingency management, with lower rates of positive symptoms at three months (coefficient –0.07, 95% CI –14 to 0) but not at 18 months (coefficient –0.04, CI –0.13 to 0.05).

What does current guidance say on this issue?

The NICE 2017 guideline on drug misuse prevention advocates targeted interventions for people at risk of drug misuse. The NICE 2007 guideline on drug misuse in over 16s advocates a nationwide training programme for NHS staff in contingency management. This guideline reports that the lack of training coupled with staff, service user and public concerns about the longevity of any behavioural change, and the possibility of an intervention appearing to reward drug use, makes the introduction of contingency management in drug misuse services a challenge.

What are the implications?

Contingency management, using the current value of shopping vouchers, is not effective in reducing cannabis use or relapse in people with early psychosis.

The researchers thought that modifying the contingency management programme design or reward level may produce different outcomes. On a positive note, the number of days of cannabis use had reduced in both groups by six months which may indicate that the psychoeducation sessions were beneficial, and they suggest that this is worth exploring further.

Citation and Funding

Johnson S, Rains LS, Marwaha S et al. A contingency management intervention to reduce cannabis use and time to relapse in early psychosis: the CIRCLE RCT. Health Technol Assess. 2019;23(45).

This project was funded by the NIHR Health Technology Assessment Programme (project number 09/144/50).

Bibliography

NHS website. Overview: psychosis. London: Department of Health and Social Care; reviewed 2016.

NICE. Drug misuse in over 16s: psychosocial interventions. CG51. London: National Institute for Health and Care Excellence; 2007, checked July 2016.

NICE. Drug misuse prevention: targeted interventions. NG64. London: National Institute for Health and Care Excellence; February 2017.

Office for National Statistics. Drug misuse: findings from the 2017/18 Crime Survey for England and Wales. Statistical Bulletin 14/18. London: Office for National Statistics; 2018.

Rash CJ, Alessi SM, Zajac K. Examining implementation of contingency management in real-world settings. Psychol Addict Behav; 2019; doi: 10.1037/adb0000496. [Epub ahead of print].

A contingency management intervention to reduce cannabis use and time to relapse in early psychosis: the CIRCLE RCT

Published on 28 August 2019

Johnson S, Rains LS, Marwaha S, Strang J, Craig T, Weaver T et al.

Health Technology Assessment Volume 23 Issue 45 , 2019

Background Cannabis is the most prevalent illicit substance among people with psychosis, and its use is associated with poorer clinical and social outcomes. However, so far, there has been limited evidence that any treatment is effective for reducing use. Contingency management (CM) is an incentive-based intervention for substance misuse that has a substantial evidence base across a range of substances and cohorts. However, to date there have been no randomised controlled trials (RCTs) of CM as a treatment for cannabis use specifically in psychosis. Objective To conduct a RCT investigating the clinical effectiveness and cost-effectiveness of CM in reducing cannabis use among Early Intervention in Psychosis (EIP) service users. Design The CIRCLE (Contingency Intervention for Reduction of Cannabis in Early Psychosis) trial was a rater-blinded, multicentre RCT with two arms. Participants were randomised 1 : 1 to either an CM arm, in which participants received CM for cannabis use alongside an optimised treatment-as-usual programme including structured psychoeducation, or a control arm in which participants received the treatment as usual only. Setting EIP services across the Midlands and the south-east of England. Participants The main eligibility criteria were EIP service users with a history of psychosis, aged 18–36 years, and having used cannabis at least once per week during 12 of the previous 24 weeks. Intervention The CM intervention offered financial incentives (i.e. shopping vouchers) for cannabis abstinence over 12 once-weekly sessions, confirmed using urinalysis. The maximum value in vouchers that participants could receive was £240. Main outcome measures The main outcome was time to relapse, operationalised as admission to an acute mental health service or hospital. The primary outcome was assessed at 18 months post inclusion using electronic patient records. Secondary outcomes assessed the clinical effectiveness and cost-effectiveness of the intervention, for which data were collected at 3 and 18 months. Results A total of 278 participants were randomised to the CM arm and 273 were randomised to the control arm. In total, 530 (96%) participants were followed up for the primary outcome. There was no significant difference in time to admission between trial arms by 18 months following consent (hazard ratio 1.03, 95% confidence interval 0.76 to 1.40). There were no statistically significant differences in most secondary outcomes, including cannabis use, at either follow-up assessment. There were 58 serious adverse events, comprising 52 inpatient episodes, five deaths and one arrest. Limitations Participant retention was low at 18 months, limiting the assessment of secondary outcomes. A different CM intervention design or reward level may have been effective. Conclusions The CM intervention did not appear to be effective in reducing cannabis use and acute relapse among people with early psychosis and problematic cannabis use.

Template content only

Expert commentary

Given the NICE CG51 recommendation to use contingency management to reduce drug use, this is a disappointing finding. Within this patient population, future areas to explore could be to simultaneously target tobacco dependence as most cannabis users will use it with tobacco.

If users could be encouraged to switch to an NRT [nicotine replacement therapy] product, there would be health benefits which may include a reduction in cannabis use. Another example could be promoting the use of forms of cannabis with less THC [Tetrahydrocannabinol, the main psychoactive component] or a more balanced CBD/THC ratio, [CBD standing for cannabidiol, the non-psychoactive component that is used to treat medical conditions].

Taking a harm reduction and a personalised approach could also include an abstinence-focused contingency intervention for patients ready and willing to accept it.

Dr Luke Mitcheson, Consultant Clinical Psychologist, South London and Maudsley NHS Foundation Trust

The commentator declares no conflicting interests