Table 4 Comparison of review types
Systematic review *excluding qualitative systematic reviews | Scoping review | Overview of systematic reviews | Rapid review | Modular review | |
|---|---|---|---|---|---|
Description | Seeks to systematically search for, appraise and synthesise research evidence, adhering to guidelines on the conduct of a review [25] | Preliminary assessment of potential size, nature and scope of available research literature [12] | Bring together, appraise and synthesise evidence in areas where multiple systematic reviews already exist [26] | Search for and review evidence within limited timeframe and scope [27] | Combines systematic modular search process with stepwise synthesis and appraisal of the evidence to produce ‘best’ evidence synthesis. Focuses on broad condition or problem for which there are competing interventions |
Expected timeframe | 24 months or more [5] | 0.5–20 months, mean length around 6 months [28] | 6–18 months [3] | < 6 months [9] | 6–18 months |
Search | Comprehensive, systematic [25] | Broad [29] | Comprehensive, systematic [26] | Limited by time and resource constraints [27] | Comprehensive, systematic. Modular search allows searching on up to 50 modular variations. |
Screening | Title-Abstract: Double independent screening recommended [30] | Title-Abstract: No established method but double independent screening Full text: No established method but double independent screening recommended [29] | Title-Abstract: No established method but double independent screening recommended Full text: No established method but double independent screening recommended [3] | Title-Abstract: Often single screening, dual screen of at least 20% of abstracts recommended [9] | Title-Abstract: Single screening with quality control measures Full text: Double independent screening |
Data Extraction | Double independent extraction [33] | Double independent extraction [34] | Single extraction, quality control measures recommended [9, 32] | Single extraction with quality control measures | |
Appraisal | Formal quality appraisal [35] | Formal quality assessment of included SRs; risk of bias of primary studies can be reported or independently assessed [37] | Formal quality appraisal often omitted [32] but recommended [9] | Relies primarily on existing quality assessment, quality assessment gaps filled as needed. | |
Synthesis | Uniform narrative and tabular synthesis on all data, often with meta-analysis [38] | Narrative and tabular synthesis, usually from systematic reviews [37] | Narrative and tabular [40] | Narrative and tabular synthesis on all data. Meta-analysis of data from “ES documents” where appropriate. |