A systematic review and Bayesian meta-analysis of interventions which target or assess co-use of tobacco and cannabis in single or multi-substance interventions.
Addiction. 2020 Jan 31;:
Authors: Walsh H, McNeill A, Purssell E, Duaso M
BACKGROUND AND AIMS: Tobacco and cannabis are commonly co-used, and evidence for the influence of co-use on quit outcomes for either substance is mixed. We sought to determine the efficacy of tobacco and/or cannabis use interventions, delivered to co-users, on cannabis and tobacco use outcomes.
METHOD: Systematic review with meta-analysis and narrative review, using five databases and author requests for co-use data. Controlled and uncontrolled intervention studies focussing on treatment of tobacco and/or cannabis use assessing use of both pre and post intervention were included. Prevention interventions were excluded. Bayesian meta-analysis was used across four outcome measures: risk ratio for tobacco and cannabis cessation post intervention separately; standardised mean change for tobacco and cannabis reduction post intervention separately. Narrative reporting of same outcome measures in non-randomised clinical trials (non-RCTs) and quality assessment of all included studies were conducted.
RESULTS: Twenty studies (12 RCTs and 8 uncontrolled) were included. Bayesian meta-analysis with informative priors based on existing data of 11 RCTs (six single substance, five multi-substance interventions) delivered to co-users (n= up to 1117) showed weak evidence for an effect on cannabis cessation (risk ratio [RR]=1.48 [0.92,2.49], studies=8) and no clear effect on tobacco cessation (RR= 1.10 [0.68,1.87], studies=9). Subgroup analysis suggested multi-substance interventions might be more effective than cannabis targeted interventions on cannabis cessation (RR= 2.19 [1.10, 4.36] versus RR=1.39 [0.75,2.74]). A significant intervention effect was observed on cannabis reduction (0.25 [0.03, 0.45], studies =9) but not on tobacco reduction (0.06 [-0.11, 0.23], studies = 9). Quality of evidence was moderate, although measurement of co-use and of cannabis use requires standardisation. Uncontrolled studies targeting both cannabis and tobacco use indicated feasibility and acceptability.
CONCLUSIONS: Single and multi-substance interventions addressing tobacco and/or cannabis have not shown a clear effect on either tobacco or cannabis cessation and reduction amongst co-users. However, dual substance interventions targeting tobacco and cannabis appear feasible.
PMID: 32003088 [PubMed – as supplied by publisher]
Source: ncbi 2