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Getting involved as a Review Author: If you have expertise in some aspect of healthcare, consider joining the relevant Cochrane Review Group. If there is not yet a group which covers your specialty, register your interest in being part of a new group. Being part of a Cochrane review group provides the support, resources and training to tackle a systematic review, and an international audience when your work is published in The Cochrane Library.


Training - face-to-face

Contact Cochrane Centres or Review Groups about local workshops and courses in review production. Some of these events are listed on the Cochrane workshops page.

Training - online

  • Open Learning Materials - learn the steps in convenient online modules which supplement the Cochrane Reviewers' Handbook in helping you gain skills and complete your review.

Training resources provided by other organizations:


Methods used in reviews

Search strategies

Access to specialised register by reviewers

The editorial base of the Cochrane Drugs and Alcohol Review Group maintains a specialized register of controlled trials.

All RCTs and CCTs from the CDAG Specialized Register can be found on the Cochrane Library by doing a search on SR-ADDICTN. Take into consideration however that when the new Cochrane Library issue come out, three months have past since the Register was submitted. In addition, the main databases searched (MEDLINE, EMBASE and CINAHL) always run one to two months behind. This means that CENTRAL on the Cochrane Library is generally around five months behind. If you need an up-to-date search contact Zuzana Mitrova (s.mitrova@deplazio.it).

 Authors should contact the editorial base before they begin their searches. The Trials Search co-ordinator will provide assistance in the preparation of the search strategy. If requested, she will launch the search strategy for each review on the main databases and the results will be forwarded to the relevant author. Hard copy of those articles not easily accessible are given to the author if available at the editorial base.
Should the author find that the trial type of a reference has been incorrectly classified, (s)he is asked to provide detailed comments.

Additional search strategies

Authors are asked to contact authors and to search citations in each trial report to obtain information on potential additional trials. In addition, authors are advised to contact pharmaceutical companies (a standard letter is included in the information pack) for unpublished studies and to check conference proceedings for additional references.

Study selection

It is the decision of individual authors to propose the type of study design that they would like to include in their reviews (see the guidelines included in "Additional information"). This information is included in the title submission form which is circulated and discussed by the editorial team before a title is registered. The authors are tutored through the editorial process by a Contact Editor with whom they are invited to discuss any methodological question that arise.

Assessment of methodological quality

Guidelines for assessing the methodological quality have been developed related both to controlled trials and to other types of studies (see Additional information).


Introduction These guidelines are intended to help reviewers of the CDAG group to check the validity of the trials to be included in reviews. The Cochrane Collaboration's reviewing is based on experimental studies, mainly RCTs and CCTs, which are considered the research designs better assuring unbiased results, when they are well conducted, for the reason that they control for unknown and unmeasured confounders. There are however several conditions in which an experimental design can be inappropriate, inadequate or even impossible , and those conditions are specially frequent in most fields of alcohol and, particularly, in drug treatment research. For this reason the editorial group of Cochrane Drugs and Alcohol Group (CDAG) considers the inclusion of the observational studies but only for topics in which there are no published RCTs or CCTs. The first section of this document discusses study designs qualified to be included in CDAG's reviews and presents the relative definitions. The second section give the criteria to be used for assessing the quality of RCTs and CCTs . For what concern the quality assessment of non randomized studies, the editorial group is still working on this topic to individuate a few and evidence based criteria to be used. In the meantime we suggest to refer to the "best" checklist for non randomised studies retrieved by Deeks JJ and coll. and considered suitable for use in a systematic review.

Section 1 - Study designs and definitions -Randomised controlled trial (RCT):
An epidemiological experiment in which subjects in a population are randomly allocated into groups, usually called 'study' and 'control' groups, to receive an experimental preventive or therapeutic procedure, manoeuvre, or intervention. The randomization methods used could be: a random numbers tables or computer generated random number. If the authors don't specify the method used but simply declare that the study is randomized, the study must be classified as randomized. -Controlled clinical trial (CCT):
An epidemiological experiment in which the treatment allocation is carried out using a so called "quasi randomized method" as alternation, patient social security numbers, days of the week, medical record numbers, day of birth or other such pseudo- or quasi-random processes.
-Controlled prospective study (CPS) Cohort prospective study:
A longitudinal study in which subjects with the same health problem are treated with different interventions and are followed up for a sufficient time to measure reliable outcome rates. Within the cohort, the researcher identifies a study group and a control group, according to the intervention to be tested and the comparison. Since the choice of the treatment remains a responsibility of the phisician in charge of the patient or is a choice of the patient itself, a crucial methodological problem of this study design is the control of the differences in baseline prognostic factors (confounding).
-Controlled before after study (CBA) An observational study, based on ecological data, where there is contemporaneous data collection before and after the intervention and an appropriate control population . The allocation is not at individual level but a population level, in other words one city or hospital receives the intervention and the control city or hospital does not. It is a study design specially pointed to measure the effects of an intervention at a population level, such as health promotion campaigns or mass media interventions.
-Interrupted time series (ITS) An epidemiological study, based on current data measured before and after an intervention occurred in the target population. The is not a control group. Since the evaluation is based on time trends, there must be a clearly defined point in time when the intervention occurred and at least three data points before and three after . Since the outcome evaluation is based on population level measures, this study design is specially aimed at the evaluation of population based interventions.

Section 2 - Guidelines for the appraisal of papers

For RCTs and CCTs, the Cochrane Collaboration recommends a specific tool for assessing risk of bias in each included study. This comprises a description and a judgement for each entry in a "Risk of bias" table, where each entry addresses a specific feature of the study.

If you have any difficulty in compiling the risk of bias table, please do not hesitate to ask for help of our quality advisor sending her the full text of the articles for which you have problems  (e.mail: minozzi.silvia@gmail.com) and specifying the nature of the problem

Data collection

For each study finally selected for inclusion, data extraction will be completed when possible directly from the paper independently by two reviewers considering the outcomes and the methodological quality. In case additional information is needed, contact is sought with the authors. The group is elaborating a list of standardised outcomes to improve the coherence between the published reviews.


Statistical guidance is one of the tasks of the contact editor to a reviewer. The group has a statistical adviser who referees every draft reviews. In general, the statistical methods described in the handbook are recommended. In particular, given that most of trials included in our reviews are based on high rates of the events considered and between trials heterogeneity, when metanalysis is possible, we suggest the use of RR with a random effect model. Reviewers are encouraged to contact the Coordinator for queries.

THE CASE OF URINE TESTS ANALYSIS (The use of urine tests analyses in meta-analysis) One of the most reliable outcomes to evaluate the effectiveness of treatments for opioid dependence is the abstinence from street heroin use. Measure of heroin use based on urinalysis for drug metabolites are preferable to self-report or collateral reports, because of their objectivity. The modalities of reporting results of urinalysis in published papers may be heterogeneous among studies, making meta-analysis (MA) difficult to be carried out. When performing a systematic review of efficacy of treatment for drug dependence, a comparative quantitative summary measure of urine test results would be required. Nevertheless those results as reported in the articles are hardly informative. Data presented as number of positive tests over number of tests cannot be properly analysed through MA. Using tests instead of the subjects as unit of analysis violates the hypothesis of independence among observations. In fact, the results of tests done in each patient are not independent. A way of conducting a meta-analysis of urine test results would be to have access to individual patient data or ask the authors for further information about the urinalysis test. In case each patient, in both groups, has given the same number of tests at the same points in time the information to ask for would be:
a)proportion of positive results (number of positive results out of the total number of tests) for each patient
b)number of positive results for each patient
In the calculation of the above statistics an important role play the missing data. In presence of missing data an assumption needs to be made. In those patients for whom the results of some tests have not been reported would be necessary to assume that those tests missing would have provided a positive result.
The figures reported in the overall results of the study would be:
a)the mean of the subject proportions of positive results (sum of the proportions divided by the number of patients)
b)the mean of number of positive results (sum of positive results divided by the number of patients).
Together with these statistics the standard deviations, the number of patients or standard errors for each treatment group should be provided.
The standardised difference could be calculated to measure the treatment effect in each study. Whereas to summarise the results so obtained among studies the standardised mean difference method could be used.
However, the success of the approach of collecting data after contacting the original authors needs a remarkable investment of resources and not least it is highly dependent on the authors' willingness to collaborate with the reviewers.
The CDAG editorial base should be contacted to discuss the feasibility and need of using those data in the meta-analysis.

Reporting of reviews

Reviewers are recommended to follow the guidance given in the Cochrane Reviewers' Handbook and can contact the Managing Editor for further clarification if required.


Editorial process


1. People interested in conducting a review with the Drugs and Alcohol Review Group should contact the Managing Editor or the Assistant Coordinator to ask for a "Title Submission Form" or download it from the Group website. The person taking responsability for the proposal (contact author) should complete the title submission form.
2.The proposed title will then be evaluated by the Editorial base and the Editorial Team and will also be circulated to the other Collaboration Groups to determine whether it is an area of common interest. Where more than one person proposes doing the same review, they are encouraged to work together. If this is not possible, responsibility for the review will be negotiated between the interested reviewers or may be given to the person who first registered the title. Where agreement cannot be reached, the final decision rests with the Co-ordinating Editor.

3. The title is registered in the Cochrane Library and the Editorial Base appoints a Contact Editor (chosen among the editors and assistant editors) and identify 2 external referees in the list of CDAG referees.  The reviewers are encouraged to attend a workshop organised by the nearest Cochrane Centre.


4. After the registration of the Title,  the Assistant Coordinator will arrange for the following materials to be sent to the review author(s):

  • details of where to obtain Review Manager software and Archie (the Cochrane Collaboration's server for managing documents and contact details);

  • links to the Cochrane Handbook, Cochrane Style Guide, Module of the CDAG, cochrane workshops, cochrane collaboration open learning materials for review authors;

  • a template of a review (a sort of framework to write the review, in RevMan5 format);

  • an example of a recently published protocol and review from the Drugs and Alcohol group's module if the review authors do not have the access to The Cochrane Library.


The editorial base will prepare the RevMan file and will inform the contact author when the file is ready to be checked out to RevMan 5 from Archie.

5. The draft protocol is expected within six months after the registration of the title. The editorial base will check all protocols for appropriateness of search strategy and adherence to QUOROM statement and template. If the review has "specific" statistical aspects to be reviewed, with special attention to heterogeneity, it is referred to the statistician advisor. The Assistant Co-ordinator will send the draft to the referees and collects their comments.The Assistant Co-ordinator will inform the contact author when the protocol has been sent to referees and will give planned timescales. All protocols are assigned a Contact Editor who verifies the scientific relevance and inclusion of appropriate issues; if necessary, asks reviewers for corrections. The Contact Editor ultimately approves the protocol for publication.

8. The referees are asked to send their feedback to the editorial base within 3 weeks.

The Assistant Co-ordinator send to the Contact Editor and the Reviewer a cover sheet in which the comments from referees are organised. The Contact Editor can express his/her opinion on the referees comments to the contact author (copying it to the Assistant Coordinator).

9.The reviewers integrate the comments from referees and Contact Editor in the final draft which is forwarded to the Assistant Coordinator along with a coversheet in which the amendments and the possible objections are highlighted.

10. The Managing editor ensure that all the steps will be done before the publication.
This process should be done within 6-8 months


11. The Trial Search Coordinator of the Group provides assistance in obtaining full articles.

12. The same peer referee process described for the protocol is performed for publishing the review. The reviewers are encouraged to contact the editorial base for help.
Authors are expected to complete the full review within 12 to 18 months of the protocol being published unless there are extenuating circumstances.


Once a review has been completed it is expected the Reviewer will update the review regularly. The Reviewer is asked to review the literature on a regular basis; at least every two years. In cases where new evidence is available the review should be updated. However, in the case where no new evidence exists the date of last update will still be modified to reflect the date of this process. The Trial Search Coordinator perform the search strategy on the group's specialised register quarterly and forwards the results to the first author. In case of significant changes the peer review process is carried out. The judgement is up to the Coordinating Editor.

CRITICISM The groups Criticism Editor is responsible for organising and summarising all post-registration criticisms. These will be forwarded to Reviewers through the Coordinator for negotiation and response.


The plain language is a brief summary of the results of the review  for consumers and non-specialist readers, it does not replace the abstract but is an additional product. Reviewers may either draft the synopsis themselves (ideally with consumer input on content and readability), or ask their Editorial Base to do it. The Cochrane Collaboration has a consumers network that help in write the plain language summary. Furthermore the Group has consumers available for help and suggestions.
The final version is submitted to the reviewer for approval.

Publication of versions of Cochrane Reviews in print journals

Authors may wish to seek co-publication of Cochrane Reviews in peer-reviewed medical journals, for The Cochrane Collaboration, there is one essential condition of co-publication: Cochrane Reviews must remain free for dissemination in any and all media, without restriction from any of them.

A Cochrane systematic review should be published either before, or at the same time as, its publication in other journals. Authors should not publish Cochrane Reviews in journals before they are ready for publication in The Cochrane Database of Systematic Reviews (CDSR).

The following passage can be provided to journal editors upon submission of a review for publication, and the letter of submission should be copied to the CRG editors for information. This policy and procedure may be new to some journal editors and may require direct discussion with the journal editor. The CRG editors should be informed of any problems encountered in this process.

"This systematic review has been prepared under the aegis of The Cochrane Collaboration, an international organisation that aims to help people make well-informed decisions about healthcare by preparing, maintaining and promoting the accessibility of systematic reviews of the effects of healthcare interventions. The Cochrane Collaboration's publication policy permits journals to publish reviews, with priority if required, but permits The Cochrane Collaboration also to publish and disseminate such reviews. Cochrane Reviews cannot be subject to the exclusive copyright requested by some journals."

Page last updated: Mon 27th Jan 2014 16:02:29 CET