Resources for review authors

 

Methods used in reviews

Search strategies

Authors should contact the Trials Search Coordinator BEFORE they begin their search. We will provide detailed and specific assistance in the preparation of your search strategy and work with you to develop it.

Access to specialised register by reviewers

Authors can search the Cochrane Library with the search term SR-VASC this will identify records on our specialist trials register. For further information please contact the trial search coordinator or review group coordinator.

Additional search strategies

The Trials Search Co-ordinator will assist authors in preparing search strategies, including advising which databases, or other sources, should be searched for their review.

Managing your searching
Once you have done your searching it is helpful to manage your records by downloading them into a reference management package such as Reference Manager, Procite or Endnote
We ask all authors to keep track of what happens to these records, and how many are discarded/used in the review. To keep track of your records please use a flow diagram, as suggested in the QUOROM statement (Moher 1999).

Study selection

We ask authors to read and to use the Cochrane Handbook for Systematic Reviews of Interventions and encourage the use of randomised controlled trials as these represent the best available evidence for effects of health care interventions. All authors must provide a QUOROM statement with their Review (Moher 1999). We encourage authors to focus on questions of clinical relevance and consequently trials with clinical event outcomes and suitable follow-up times are preferred. We ask authors to use forms to record eligibility and to help them decide whether a study is included or excluded. The editorial base can provide authors with examples of these forms. Ideally two authors should independently select trial reports for inclusion using the eligibility forms and differences should be resolved by discussion. These forms are useful to record why specific trial reports were excluded from the systematic review.

Assessment of methodological quality

We ask authors to follow the methods in the Cochrane Handbook for Systematic Reviews of Interventions (www.cochrane-handbook.org). Standard scales are not recommended. We advise authors to collect informationon sequence generation, allocation concealment, blinding of participants,personnel and outcome assessors, incomplete outcome data and selective outcomereporting. Effects of methodological quality of included studies may beexamined depending on the authors' views. As yet there is no consensus on theoptimum method to assess the methodological quality of randomised controlledtrials. Scoring the quality of RCTs can be disadvantageous and is viewed withsome controversy (Juni et al 1999).

The Cochrane Heart Group recommend authors address the following criteria intheir assessment of quality of RCTs:

1 Was the allocation sequence adequately generated?

2 Was allocation adequately concealed?

3 Was knowledge of the allocated intervention adequatelyprevented during the study?

4 Were incomplete outcome data adequately addressed?

5 Are reports of the study free of suggestion of selectiveoutcome reporting?

6 Was the study apparently free of other problems that couldput it at a high risk of bias?

Data collection

We ask authors to use a form on which to record the data they will use from each study for their systematic review. These are called "data extraction forms". The editorial base can provide authors with examples of these forms. Ideally two authors should independently complete data extraction forms and then resolve differences by discussion and re-examination of study reports. These forms are helpful for inputting data for the systematic review and, if included in the review, meta-analysis.

Verification of data is the responsibility of the authors.

Unpublished data should be sought where feasible. For drug trials, rare adverse events should be commented upon in the discussion of the Review and evidence from case reports and large post-marketing surveillance case series cited as appropriate.

We request that authors abstract data on all clinical event outcomes and also on risk factor changes (where appropriate). Physiological, pathological, psychological, quality of life or radiological outcomes may be abstracted depending on the nature of the question the review seeks to answer.

Analysis

We ask authors to follow the methods of analysis in the Cochrane Handbook for Systematic Reviews of Interventions. Analysis should be performed in RevMan. Statistical support is available in the form of the Cochrane Handbook for Systematic Reviews of Interventions, from the Cochrane Heart Group editorial office and from statistical advisors to the group. Please restrict the number of analyses to those which are clinically appropriate, as if many analyses are prepared some could reach cut offs for statistical significant by chance. Please take care not to pool data from heterogeneous trials - or where data itself are too varied to merit pooling.

Statistical methods for the comparison of clinical events recommended are Odds ratios, Peto odds ratios or Risk ratios (relative risk) and for continuous data difference in means. 95% confidence intervals and, where possible, precise P values should be reported for all effect size estimates for both individual trials and pooled estimates. Heterogeneity between trials should always be explored by considering the clinical setting, patients involved and the intervention. Sub-group and sensitivity analyses may be appropriate. We recommend to those who want to include cross over trials in their systematic reviews the analytical methods described by Elbourne et al 2002. For information on any aspects of analysis or for statistical assistance please contact the Cochrane Heart Group editoral office.

Reporting of reviews

We encourage authors to publish their reviews in other journals. We ask that authors contact the Cochrane Heart Group office when considering publishing in another journal. Many other journals allow dual publication of systematic reviews in The Cochrane Library and their journal. We ask all authors to publish their review on The Cochrane Library (the Cochrane Database of Systematic Reviews) before publishing in another journal or to arrange "simultaneous" publication. Authors must complete a Permissions request form which is available from the website of the Heart Group or the Collaboration's website. This form must be sent to the permissions office of Wiley and sons. There is some standard text we like other journals to publish with the review; please ask the Cochrane Heart Group editorial office for this information. Commentaries describing Cochrane systematic reviews may be published in other journals a permission request form is required for this.

References
Elbourne DR, Altman DA, Higgins JPT, Curtin F, Worthington HV, Vail A. Meta-analyses involving cross-over trials: methodological issues. International Journal of Epidemiology 2002; 31: 140-149

Juni P, Witschi A, Bloch R, Egger M. The hazards of scoring the quality of clinical trials for meta-analysis. 1999. JAMA, 282, 11, 1054-1060.

Moher D, Cook DJ, Eastwood S, Olkin I, Rennie D, Stroup DF, for the Quorom Group. Improving the quality of reports of meta-analyses of randomised controlled trials: the Quorom Statement. The Lancet, 1999, Vol 354, 1896-1900.)