Selective reporting is when authors of primary research or systematic reviews report on outcomes that weren’t pre-specified when the research was planned, or when outcomes that were pre-specified and addressed get omitted from the article that get published. This happens especially when the results of the outcomes were not desirable or significant.
Selective reporting is a problem as it introduces the risk of bias in research, which can have an enormous impact on healthcare decision-making. An approach to try and combat the problem is to encourage and enforce the prospective registration of research. This will allow that readers of research can compare the set of pre-specified outcomes in the protocol with the outcomes reported in the published article, and decide if all important outcomes were sufficiently addressed. The policy of many healthcare journals nowadays is to only accept articles for publication if the authors can provide a protocol registration number.
The Centre for Evidence-based Health Care supports and encourages the prospective registration of trials and systematic reviews. Examples of where trials can be prospectively registered include:
- The International Clinical Trials Registry Platform (ICTRP) of the World Health Organisation (WHO) is an international register of clinical trials that believes that “registration of all interventional trials is a scientific, ethical and moral responsibility”. (http://www.who.int/ictrp/en/)
- The Pan African Clinical Trials Registry (PACTR) is a regional register of clinical trials conducted in Africa. The PACT is the only WHO-endorsed registry in Africa. (http://www.pactr.org/ )
Systematic reviews on health and social care topics can be prospectively registered in PROSPERO. This International Prospective Register of Systematic Reviews “aims to provide a comprehensive listing of systematic reviews registered at inception to help avoid unplanned duplication and enable comparison of reported review findings with what was planned in the protocol”. (http://www.crd.york.ac.uk/NIHR_PROSPERO/)
Embarking on a systematic review:
A few tips on where to start and the process to follow
What is your question?
- It is very important to start with a clear question for your review
- Use PICO* format where P stands for participants, I for intervention, C for control and O for outcomes
Are there existing systematic reviews answering your question?
- Search for existing reviews related to your topic – check the Cochrane Database of Systematic reviews and the Database of Abstracts of reviews of effects in www.thecochranelibrary.com
- Introduction to Systematic Reviews, developed by the Cochrane Collaboration. This 45 minutes click-through module describes the history, aims and structure of The Cochrane Collaboration; discuss the rationale for systematic reviews, and outlines the process of undertaking a Cochrane Review. http://training.cochrane.org/authors/intervention-reviews/olms/introduction-systematic-revie
- This refines your question formulation
- Also check registered titles and protocols
Get together your review team
- Content expertise important (co-author)
- Methodological expertise important (co-author)
- Statistical expertise may be necessary (co-author or consultant)
Register the title of your review
- If confident that there are no existing reviews (i.e. your question fills a gap in the literature), proceed registering your title
- If a Cochrane or Campbell review, then register with the relevant review group
- If not, register with PROSPERO (title and protocol**)
Develop your protocol** where you need to provide detail
- Rationale for the review
- Criteria for considering studies
- Approach to identify studies (searching)
- Data management and analysis
- Project management (e.g. timeline, who’s responsible for what
Conduct your review
- Follow your protocol
- Information specialist to assist with searches
- Seek statistical advice if needed
Report your review
- Look at good quality published reviews for examples
- Be transparent
- PRISMA Reporting guidelines
Publish and disseminate
*PICO can also be expanded to PICOTS to also include T for timepoint (e.g. long term) and S for study design (e.g. randomised controlled trials). Furthermore, the PICO format can be adapted for formulating questions about diagnostic accuracy, screening, risk factors, aetiology, prognosis, prevalence, etc.
- GRADE webinars, developed by the Department of Clinical Epidemiology and Biostatistics of McMaster University and in collaboration with the Cochrane Collaboration. These audio-visual presentations (between 8 and 20 minutes each) take you step by step through the process of GRADEing evidence from systematic reviews on questions of interventions.http://cebgrade.mcmaster.ca/Intro/index.htmlhttp://fhsed.mcmaster.ca/onlineModules/GRADE/outcomes/http://cebgrade.mcmaster.ca/RoB/index.html
- The EQUATOR Network website is a resource centre for good reporting of health research studies
- Systematic reviews of randomised controlled trials – PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses.
- Cochrane “Standards for the reporting of new reviews of interventions”
- Systematic reviews of observational studies – MOOSE (Meta-analysis Of Observational Studies in Epidemiology) is a guideline for reporting systematic reviews and meta-analyses of observational studies.
- Randomised controlled trials – CONSORT (Consolidated Standards of Reporting Trials) includes various initiatives developed by the CONSORT Group to alleviate the problems arising from inadequate reporting of randomized controlled trials (RCTs).
- Observational studies – STROBE (STrengthening the Reporting of OBservational studies in Epidemiology).
- Diagnostic accuracy studies – STARD (STAndards for the Reporting of Diagnostic accuracy studies) aims to improve the accuracy and completeness of reporting of studies of diagnostic accuracy.