Systematic review reporting guide, 2015

Volume 41-4, April 2, 2015: Scientific writing

Scientific writing

Systematic review reporting guide



Systematic reviews summarize the state of knowledge about a topic. They clarify both what is known and what needs further study and are used to stay up-to-date, to inform the development of advisory statements and clinical practice guidelines and to identify priorities for future research. They are typically 2,000-2,500 words in length - excluding the abstract, tables and references.

The Canada Communicable Disease Report (CCDR) endorses the widely-accepted reporting guideline, the Preferred Reporting Items of Systematic reviews and Meta-Analyses (PRISMA)Footnote 1. This guide was initially developed for health care interventions and has now been adapted for other usesFootnote 2,Footnote 3,Footnote 4.

Table 1 provides the PRISMA checklist. Figure 1 illustrates a flow diagram that identifies how the initial number of studies identified during a literature search was pared down to the studies for review.

There are some additional considerations for systematic reviews on infectious disease topics. These include the need to consider differences across studies in laboratory methods used for the identification of infectious diseases, the presence or degree of antibiotic resistance and how case definitions were used to interpret laboratory results. Generic names are used to identify identify antibiotics or vaccines; brand names may be noted in brackets upon first use.

As with all submissions, check CCDR's Information for authors (published in January every year with the first issue of each new volume) for general manuscript preparation and submission requirements.

Table 1: PRISMA Checklist for systematic reviews
Reporting item NoTable 1 - Note a Description
Title 1 Identify the report as a systematic review, meta-analysis or both.
Structured summary 2 Provide a structured abstract including the following subheadings: Background; Objectives; Data sources; Study selection; Synthesis; Conclusions and, when applicable, systematic review registration number.Table 1 - Note b
Rationale 3 Describe the rationale for the review in the context of what is already known.
Objectives 4 Provide an explicit statement of questions being addressed with reference to Participants, Interventions, Comparisons, Outcomes and Study design (PICOS).
Protocol and registration 5 Indicate if a review protocol exists, if and where it can be accessed (e.g., website address) and, if available, provide registration information including registration number.
Eligibility criteria 6 Specify study characteristics (e.g., PICOS, length of follow-up) and report characteristics (e.g., years considered, language, publication status) used as criteria for eligibility, giving rationale.
Information sources 7 Describe all information sources (e.g., databases with dates of coverage, contact with study authors to identify additional studies) in the search and date last searched.
Search 8 Present full electronic search strategy for at least one database, including any limits used, such that it could be repeated.
Study selection 9 State the process for selecting studies (e.g., screening, eligibility, included in systematic review and, if applicable, included in the meta-analysis).
Data collection process 10 Describe method of data extraction from reports (e.g., piloted forms, independently, in duplicate) and any processes for obtaining and confirming data from investigators.
Data items 11 List and define all variables for which data were sought (e.g., PICOS, funding sources) and any assumptions and simplifications made.
Risk of bias in individual studies 12 Describe methods used for assessing risk of bias of individual studies (including specification of whether this was done at the study or outcome level) and how this information is to be used in any data synthesis.
Summary measures 13 State the principal summary measures (e.g., risk ratio, difference in means).
Synthesis of results 14 Describe the methods of handling data and combining results of studies, if done, including measures of consistency (e.g., I2) for each meta-analysis.
Risk of bias across studies 15 Specify any assessment of risk of bias that may affect the cumulative evidence (e.g., publication bias, selective reporting within studies).
Additional analyses 16 Describe methods of additional analyses (e.g., sensitivity or subgroup analyses, meta-regression) and if done, indicate which were pre-specified.
Study selection 17 Provide numbers of studies screened, assessed for eligibility and included in the review, with reasons for exclusions at each stage, ideally with a flow diagram.
Study characteristics 18 For each study, present characteristics for which data were extracted (e.g., study size, PICOS, follow-up period) and provide the citations.
Risk of bias within studies 19 Present data on risk of bias of each study and, if available, any outcome level assessment (see item 12).
Results of individual studies 20 For all outcomes considered (benefits or harms), present, for each study: simple summary data for each intervention group and effect estimates and confidence intervals, ideally with a forest plot.
Synthesis of results 21 Present the main results of the review. If meta-analyses are done, include for each, confidence intervals and measures of consistency.Table 1 - Note c
Risk of bias across studies 22 Present the results of any assessment of risk of bias across studies (see Item 15).
Additional analysis 23 Provide the results of additional analyses, if done (e.g., sensitivity or subgroup analyses, meta-regression [see Item 16]).
Summary of evidence 24 Summarize the main findings including the strength of evidence for each main outcome; consider their relevance to key groups (e.g., healthcare providers, users and policy makers).
Limitations 25 Discuss limitations at study and outcome level (e.g., risk of bias) and at review-level (e.g., incomplete retrieval of identified research, reporting bias).
Conclusions 26 Provide a general interpretation of the results in the context of other evidence  and implications for future research.
Funding 27 Describe the sources of funding for the systematic review and other support (e.g., supply of data) and role of funders for the systematic review.
Table 1 - Note a

No: Number

Return to Table 1 notea referrer

Table 1 - Note b

Description of the abstract has been modified for the Canada Communicable Disease Report (CCDR).

Return to Table 1 noteb referrer

Table 1 - Note c

Reflects correction as noted on:

Return to Table 1 notec referrer

Figure 1: PRISMA 2009 flow diagram

Figure 1
Text equivalent for figure 1PRISMA 2009 flow diagram

This is a flow diagram that identifies how all the records for the study were identified, assessed and then either included or excluded. Two boxes at the top of the page for the study (first level) identify the number of records identified through 1) database searching or 2) other sources. Both boxes then point to a second level box showing the number of records after duplicates removed.  This points to a third level box showing number of records screened. From here there are two arrows; one pointing horizontally to number of records excluded and one pointing to the fourth level for number of full-text articles assessed for eligibility. This box has two arrows; one pointing horizontally to number of full text articles excluded, with reasons and one pointing vertically to the fifth level for studies included in the qualitative synthesis. This then points to a sixth level box showing the number of studies included in the quantitative synthesis (meta-analysis).

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