Psychotherapeutic interventions for cannabis abuse and/or dependence in outpatient settings
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To evaluate the efficacy of psychosocial interventions for cannabis abuse or dependence.
Background
Population‐based studies have consistently revealed that cannabis is the most widely used illicit substance in many Western countries including Europe (EMCDDA 2003) North America and Australia (Copeland 2001; Donnelly 1994). In many countries, among those accessing treatment for drug use disorders, cannabis is more commonly the principal drug of concern than heroin (AIHW 2003; EMCDDA 2003).
The diagnostic criteria for cannabis use disorder including abuse and dependence are described in the DSM‐IV (DSM‐IV R) and the ICD‐10 (WHO 1992). Cannabis use disorder is the most commonly occurring illicit substance use disorder in the general population.
According to DSM‐IV, cannabis abuse is characterized by a pattern of cannabis use that causes clinically significant distress or impairment in the absence of dependence. The 12‐month prevalence of cannabis abuse in general population has been estimated at 0.7% (Swift 1998).
Epidemiological studies estimated that around 6% of those who had used cannabis in the past year met DSM‐IV criteria for cannabis dependence (Grant 1998). This is higher in countries such as Australia where among those having used cannabis more than five times in the previous year almost one third (31.7%) met criteria for cannabis use disorder (21% dependence and 10.7% abuse) (Swift 1998).
Despite these high levels of problem use, only a minority seek assistance from a health professional (Copeland 1999; Degenhardt 2003). The demand for treatment for cannabis use disorder, nonetheless, is increasing internationally. In 1999, the US Treatment Episode Data Set recorded more than 220 000 admissions for primary cannabis use to publically funded substance abuse treatment (SAMHSA 2002). This represented 14% of admissions to these facilities, and a doubling of the rate since 1993. In 2000, that dataset reported that cannabis accounted for 61% of all adolescent admissions (SAMHSA 2003). Australia has also seen a doubling in the rates of cannabis treatment seeking nationally from 2000/1 to 2001/2, with a rate of 21% overall and 45.5% of those aged less than 20 years (AIHW 2003). In Europe, the percentage of clients seeking treatment for cannabis as their main drug ranges from 2.5% in Portugal to 24% in Germany (EMCDDA 2003). There has been a concomitant increase in the number of emergency department cannabis‐related episodes in the United States. Taking into account changes in population, there had been a 139% increase in such presentations reported from 1995 to 2002 (SAMHSA 2003).
Clients seeking treatment for cannabis use exhibit social impairment (family member complaining, lost friends, financial difficulty, impaired work or school performance, legal problem) and psychiatric distress (somatization, depression, anxiety, irritability, phobic anxiety, paranoid ideation, psychoticism), report multiple adverse consequences (inability to stop using, feeling bad about abusing, procrastinating, loss of self‐confidence, memory loss and withdrawal symptoms) associated with cannabis use and repeated unsuccessful attempts to stop using (Budney 1999; Budney 2000; Stephens 1993). Their use persisted despite negative consequence, and most perceived themselves as unable to quit (Budney 2000; Copeland 2001).
Until recently, relatively little research has focused on the treatment of cannabis abuse or dependence. A major factor contributing to the lack of clinical research focused on this disorder is that many believed that cannabis use did not produce a dependence syndrome, thus treatment to assist with quitting was not desired or needed (McRae 2003). However, since a survey was carried out in 1987 in the USA (Roffman 1987), reports confirm that individuals with cannabis‐related problems readily respond to advertisements for treatment, but the majority do not use others substances (Budney 1999; Copeland 2001; Stephens 1993). Evidence of adverse effects on health and changes in societal tolerance of drug use suggest that there will be an increase in the number of cannabis users seeking to quit.
The cannabis‐specific program in the USA may have legitimized the need for treatment related to cannabis abuse or dependence, reduced stigma associated with drug abuse treatment, and attracted clients who otherwise would be reluctant to approach counseling (Copeland 2001; Stephens 1993). However, despite the large number of cannabis users who seek or may need treatment only a few randomized clinical trials exist to discuss the most effective interventions. Randomized controlled trials of outpatient treatments have compared interventions such as cognitive behavioral therapy, motivational enhancement therapy, relapse prevention, family therapy approaches, group therapy and support groups. These interventions have been delivered as group and individual interventions.
Treatment development and efficacy studies targeting cannabis abuse or dependence began to appear in the scientific literature during the 1990s. To our knowledge, there is no systematic review published in the existing literature on the treatment of cannabis abuse or dependence including psychotherapeutic advances.
The purpose of this systematic review is to evaluate the effectiveness of psychotherapeutic interventions for cannabis abuse or dependence.
Objectives
To evaluate the efficacy of psychosocial interventions for cannabis abuse or dependence.
Methods
Criteria for considering studies for this review
Types of studies
All relevant randomized controlled studies examining a psychotherapeutic intervention for cannabis dependence or abuse in comparison with a delayed‐treatment control group or combinations of psychotherapeutic interventions. Non‐randomized trials will be excluded from this systematic review and meta‐analysis.
Types of participants
All participants who met diagnostic criteria for cannabis abuse or dependence, assessed by Diagnostical and Statistical Manual of Mental Disorders (DSM IV) OR Internationa Classification of Diseases (ICD‐10) and sought treatment in outpatient settings will be included. All adult participants (>18) will be included regardless of gender, and nationality. The history of previous treatments will be considered, but it is not an eligibility criterion. Exclusion criteria will be current dependence on alcohol or any other drug (except nicotine).
Types of interventions
Experimental intervention
One treatment or more than one treatment for the management of cannabis abuse or dependence delivered in a group or individual model in an outpatient setting.
Control intervention
Non‐intervention (untreated control group or delayed control group) OR
Intervention other of which considered in the intervention group
The intervention considered may include:
(1) Cognitive behavioral therapy
(2) Motivational enhancement therapy
(3) Family support network
(4) Family therapy
(5) Combination of the above
Types of outcome measures
Primary outcomes:
(1) Severity of Dependence/abuse measured as Addiction severity measured with a standardized questionnaire (e.g. Addiction Severity Index (McLellan 1980); Severity of Dependence Scale (Swift 1998).
(2) Self‐reported use of cannabis (number of day, time per day) with confirmation by biological analysis (urinalysis, or hair/saliva analyses)
(3) Dropout from treatment, measured as the absolute number of participants at the end of the follow‐up;
Secondary outcomes:
(4) Frequency of other substances intake, self‐reported
(5) Level of cannabis‐related problems: medical problems, legal problems, social and family relations, employment an support, assessed by questionnaire such as the Cannabis Problems Questionnaire (Copeland 2001)
Search methods for identification of studies
We will develop detailed search strategies for the identification of studies to include in the review.
These will be based on the search strategy developed for MEDLINE but revised appropriately for each database. The search strategy will combine the subject search with phases 1 & 2 of the Cochrane Sensitive Search Strategy for Randomised Controlled Trials (RCTs) as published in Appendix 5b2 of the Cochrane Reviewers' Handbook (Alderson 2004). There will be no language restrictions.
We will search :
(1) Cochrane Drugs and Alcohol Group'Register of Trials (August 2004) using the following terms: diagnosis=cannabis and intervention=psychosocial
(2) Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2004)
¢EMBASE (January 1988 to August 2004)
¢PsycInfo (1985 to October 2004)
¢CINHAL (1982 to october 2004)
¢Toxibase [add data range]
with no language and publication restrictions.
(3) MEDLINE (January 1966 to August 2004):
(a) Search strategy to locate cannabis abuse:
1.exp substance ‐related disorders/
2.addict$.ab,ti
3.abus$.ab,ti
4.dependenc$.ab,ti.
5.(excessive$ adj use$).ab,ti.
6.(use$ adj disorder$).ab,ti
7.1 or 2 or 3 or 4 or 5 or 6
8.exp Cannabis/
9.cannabis.ab,ti
10.marijuana.ab,ti.
11.marihuana.mp
12.hashish.mp
13.8 or 9 or 10 or 11 or 12
(b) Search strategy to locate interventions:
14.Psychotherapy/ or psychoterapy.tw
15.Psychodynamic therapy.tw
16.Behavior therapy OR behaviour therapy.tw.
17.Behavior management OR behaviour management.tw.
18.Behavioral contracting.tw. OR behavioural contracting.tw.
19.Cognitive therapy OR Cognitive therapy.tw.
20.Cognitive behavior therapy.tw OR Cognitive behaviour therapy.tw.
21.Counseling OR counselling.tw.
22.Relaxation OR relaxation techniques OR mind and body relaxation technique OR relaxation therapy.tw. OR progressive relaxation.tw.
23.Imagery (Psychotherapy) OR guided imagery.tw
24.Biofeedback (Psychology) OR biofeedback.tw.
25.Family therapy OR family therapy$.tw
26.14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24
27.6 and 13 and 26
28.limit 27 to human
MANUAL SEARCHES
We will check the reference lists of all potentially eligible studies obtained as full reports to identify any further studies not retrieved by the electronic search. We will also obtain full reports of review articles retrieved by the search and check these for other relevant citations. In addition, we will contact authors of included studies and experts in the field for leads on unpublished or difficult to find studies.
Data collection and analysis
Selection of trials
Two authors will independently screen the titles and abstracts of all publications, obtained by the search strategy. We will obtain all potentially eligible studies as full articles and these will be assessed independently for inclusion by the two authors. In doubtful or controversial cases, the authors will discuss all identified discrepancies and reach consensus on all items. If consensus is still not reached, they will refer to the original author to solve the problem. Experts familiar with the language will manage potential language problems in retrieved studies. When key information relevant to the systematic review is missing, we will contact investigators and ask them to provide additional data and clarifications. If the majority of trials use the same scale or specific outcome measures, we will ask the primary investigators of the trials that do not report these specific measures to provide relevant data, if available.
We will accept all randomized trials of psychotherapeutic interventions in cannabis dependence or abuse regardless of type of psychotherapy, model or duration of therapy.
Whenever reports pertain to overlapping patients, we will retain only the largest study, to avoid duplication of information.
Assessment of the methodological quality
In order to limit bias, gain insight into potential comparisons and guide interpretation of findings, two authors, using the criteria described in the Cochrane Handbook, will independently assess the methodological quality of the eligible studies. In the context of a systematic review, the validity of a study is the extent to which its design and conduct are likely to prevent systematic errors, or bias (Moher 1995).
Allocation concealment.
We will use the following criteria:
(A) adequate allocation concealment, central randomization (e.g. allocation by a central office unaware of subject characteristics), pre‐numbered or coded identical bottles or containers which are administered serially to participants, drug prepared by the pharmacy, serially numbered, opaque, sealed envelopes, on‐site computer system combined with allocations kept in a locked unreadable; computer file that can be accessed only after the characteristics of an enrolled participant have been entered or other description that contained elements convincing of concealment.;
(B) unclear allocation concealment: when the authors either did not report an allocation concealment approach at all or report an approach that did not fall in the category A or C.
(C) inadequate allocation concealment: alternation or reference to case numbers, dates of birth, day of the week. Any procedure that is entirely transparent before allocation, such as an open list of random numbers or other description that contained elements convincing of not concealment
Performance bias:
blinding of those providing and receiving the intervention
(A) double blind
(B) single blind (blinding of participants)
(C) unclear
(D) no blinding
Attrition Bias
(A) Loss to follow up completely recorded
(B) Loss to follow up incompletely recorded
(C) Unclear or not done
Detection bias :
Blinding of the outcome assessor:
A) Blind to treatment allocation at outcome assessment
B) Not blind to treatment allocation at outcome assessment
C) Unclear
Intention to treat analysis
A) Intention to treat analysis performed
B) Intention to treat analysis not performed
C) Unclear
Data extraction
The authors will independently extracted data.
Data analysis
Dichotomous outcome will be analyzed by calculating relative risks (RR) for each trial (95% confidence intervals) The RR from the individual trials will be combined through meta‐analysis. When overall results will be significant, the number needed to treat to produce one outcome will be calculated by combining the overall RR with an estimate of prevalence of the event in the control group of the trials.
Continuous outcomes will be analyzed according to their difference in mean treatment effects and its standard deviation.
Heterogeneity in the results of the trials will be assessed both by inspection of graphical presentations and by calculating a test of heterogeneity. Possible reasons for heterogeneity will be specified (response differs according to the different interventions, according to the characteristics of patients included in trials). It will be assessed by looking at separate subgroups of trials.
Tables will be used to display characteristics of eligible trials including trials that will be excluded with the reasons for exclusion.
Outcomes will be also presented graphically. We will use Review Manager software developed by the Cochrane Collaboration to organize and process the results. If possible, we will perform an intention‐to‐treat analysis. In addition, we propose to carry out a modified approach of this analysis. This will entail, excluding from analysis randomized patients that do not attend the first day of treatment, without receiving any medication, according to Lehert 1993. We will compare the modified and traditional intention‐to‐treat results.
Data synthesis
We will perform meta‐analysis when appropriate for each of the pre‐specified outcomes. Both fixed and random effects models will be used. Continuous measures will be summarized using weighted mean differences and binary outcomes will be summarized using risk differences, risk ratios, and odds ratios. Between‐study heterogeneity will be estimated with the chi‐square based Q statistic and this will also be expressed by the I‐square estimates. We will perform calculations in RevMan, Meta‐Analyst, and Comprehensive Meta‐analysis software.
