Abstract: We included a total of 52 trials (6923 participants). The psychosocial interventions considered in the studies were: cognitive behavioural therapy (19 studies), contingency management (25 studies), motivational interviewing (5 studies), interpersonal therapy (3 studies), psychodynamic therapy (1 study), 12-step facilitation (4 studies). We judged most of the studies to be at unclear risk of selection bias; blinding of personnel and participants was not possible for the type of intervention, so all the studies were at high risk of performance bias with regard to subjective outcomes; the majority of studies did not specify whether the outcome assessors were blind. We did not consider it likely that the objective outcomes were influenced by lack of blinding. The comparisons made were: any psychosocial intervention versus no intervention (32 studies), any psychosocial intervention versus TAU (6 studies), and one psychosocial intervention versus an alternative psychosocial intervention (13 studies). Five of included studies did not provide any useful data for inclusion in statistical synthesis. We found that, when compared to no intervention, any psychosocial treatment: reduced the dropout rate (risk ratio (RR): 0.83, 95% confidence interval (CI) 0.76 to −0.91, 24 studies, 3393 participants, moderate quality evidence); increased continuous abstinence at the end of treatment (RR: 2.14, 95% CI 1.27 to −3.59, 8 studies, 1241 participants, low quality evidence); did not significantly increase continuous abstinence at the longest follow-up (RR: 2.12, 95% CI 0.77 to −5.86, 4 studies, 324 participants, low quality evidence); significantly increased the longest period of abstinence: (standardised mean difference (SMD): 0.48, 95% CI 0.34 to 0.63, 10 studies, 1354 participants, high quality evidence). However, it should be noted that the in the vast majority of the studies in this comparison the specific psychosocial treatment assessed in the experimental arm was given in add on to treatment as usual or to another specific psychosocial or pharmacological treatment which was received by both groups. So, many of the control groups in this comparison were not really untreated. Receiving some amount of treatment is not the same as not receiving any intervention, so we could argue that the overall effect of the experimental psychosocial treatment could be smaller if given in add on to TAU or to another intervention than if given to participants not receiving any intervention; this could translate to a smaller magnitude of the effect of the psychosocial intervention when it is given in add on. When compared to TAU, any psychosocial treatment reduced dropout rate (RR: 0.72, 95% CI 0.59 to 0.89, 6 studies, 516 participants, moderate quality evidence), did not increase continuous abstinence at the end of treatment (RR: 1.27, 95% CI 0.94 to 1.72, 2 studies, 224 participants, low quality evidence), did not increase longest period of abstinence (MD −3.15 days, 95% CI −10.35 to 4.05, 1 study, 110 participants, low quality evidence). No studies in this comparison assessed the outcome of continuous abstinence at longest follow-up. There were few studies comparing two or more psychosocial interventions, with small sample sizes and considerable heterogeneity in terms of the types of interventions assessed. None reported significant results. None of the studies reported harms related to psychosocial interventions. The addition of any psychosocial treatment to treatment as usual (usually characterised by group counselling or case management) probably reduces the dropout rate and increases the longest period of abstinence. It may increase the number of people achieving continuous abstinence at the end of treatment, although this might not be maintained at longest follow-up. The most studied and the most promising psychosocial approach to be added to treatment as usual is probably contingency management. However, the other approaches were only analysed in a few small studies, so we cannot rule out the possibility that the results were not significant because of imprecision. When compared to TAU, any psychosocial treatment may improve adherence, but it may not improve abstinence at the end of treatment or the longest period of abstinence. The majority of the studies took place in the United States, and this could limit the generalisability of the findings, because the effects of psychosocial treatments could be strongly influenced by the social context and ethnicity. The results of our review do not answer the most relevant clinical question, demonstrating which is the most effective type of psychosocial approach. Further studies should directly compare contingency management with the other psychosocial approaches.

Plain-language summary: We looked at 52 randomised controlled trials (studies where people were allocated at random to one of two or more treatment or control groups) in this review. On average, the interventions lasted about 16 weeks, while investigators followed up participants for 6 to 12 months. The studies examined different kinds of psychosocial interventions: cognitive behavioural therapy (19 studies), contingency management (25 studies), motivational interviewing (5 studies), interpersonal therapy (3 studies), psychodynamic therapy (1 study) and 12-step facilitation (4 studies). Forty-one studies took place in the United States, four in Spain, three in Australia, two in Switzerland and two in the UK. We included a total of 6923 participants with an average age of 36 years. The proportion of males is 63%. The comparisons made were: any psychosocial versus no intervention (32 studies), any psychosocial versus treatment as usual (6 studies), and one psychosocial intervention versus an alternative psychosocial intervention (13 studies). Five of the included studies did not provide any useful data for inclusion in statistical synthesis. We found that, compared to no intervention, any psychosocial intervention probably improves treatment adherence and may increase abstinence at the end of treatment; however, people may not be able to stay clean several months after the end of treatment. Finally, we found that people undergoing specific psychosocial interventions stay clean for a longer time without using stimulants. However, the vast majority of the studies we looked at assessed a specific psychosocial treatment added to treatment as usual or compared it to another specific psychosocial or pharmacological treatment. So, control groups were not really untreated. This could have led to an underestimation of the true effect of the psychosocial interventions. We found that, when compared to TAU, any psychosocial treatment probably improves adherence but may not improve abstinence at the end of treatment nor help participants to stay clean for a longer time. We could not draw any conclusions on which is the most effective psychosocial treatment based on direct comparisons. Most of the studies took place in the United States, and this could limit the generalisability of the findings, because the effects of psychosocial treatments could be strongly influenced by the social context and ethnicity. None of the studies reported harms related to psychosocial interventions. The quality of evidence was moderate for adherence to treatment but low for abstinence.