9.8.6 Systematic Reviews and Meta-analysis

Systematic Reviews and Meta-Analysis: Describes the QUORUM Statement for Improving the Quality of Reports of Meta-Analyses of Randomized Controlled Trials and Critically Appraises a Systematic Review

Systematic reviews and meta-analyses are important tools for synthesizing evidence and providing a high-level overview of a particular research question. A systematic review is a comprehensive and structured approach to identifying, evaluating, and synthesising all relevant research evidence on a particular research question. A meta-analysis, on the other hand, is a statistical technique used to combine the results of multiple studies to obtain a summary effect size.

The QUOROM Statement:

The QUOROM (Quality of Reporting of Meta-Analyses) statement was developed to improve the reporting of meta-analyses of randomized controlled trials (RCTs). The statement consists of a 27-item checklist and flow diagram that can be used by authors, reviewers, and readers of meta-analyses to assess the quality of reporting. The items address the quality of the study, the methods of the analysis, and the presentation of the results.

Some of the key items on the QUOROM checklist include a clear statement of the research question, a description of the search strategy used to identify relevant studies, an assessment of the quality of the included studies, a description of the statistical methods used in the analysis, and a clear presentation of the results. The flow diagram provides a visual representation of the process used to identify, screen, and include/exclude studies for the meta-analysis.

The QUOROM statement has been updated and replaced by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement, which includes additional items relevant to systematic reviews and meta-analyses of other study designs beyond RCTs.

A well-conducted meta-analysis that adheres to the QUOROM/PRISMA guidelines can provide valuable information to inform clinical practice and policy decisions. However, it is important to critically appraise the quality of the meta-analysis and consider factors such as the heterogeneity of the included studies and the potential for publication bias.

Systematic review:

The process of conducting a systematic review involves several key steps. These include defining the research question, identifying relevant studies, assessing the quality of the included studies, extracting data from the included studies, and synthesizing the results. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement provides a framework for reporting systematic reviews and meta-analyses in the medical literature.

Critical appraisal of a systematic review is an essential step to determine the reliability and validity of its findings. A systematic review is a comprehensive and structured synthesis of evidence that aims to answer a specific research question. Here are some steps to critically appraise a systematic review:

• Check the research question and objectives: Determine whether the research question is clearly stated and whether the objectives of the systematic review are appropriate.

• Evaluate the search strategy: Examine whether the search strategy is comprehensive, including databases and grey literature, and whether the search terms are appropriate for the research question.

• Assess the study selection process: Determine if the study selection process is clearly defined and whether the inclusion and exclusion criteria are appropriate for the research question.

• Evaluate the data extraction process: Examine whether the data extraction process is clearly defined, whether data were extracted independently by two reviewers and whether there is any potential for bias in the data extraction process.

• Assess the quality assessment of included studies: Determine if the quality assessment of included studies is clearly defined and whether it is appropriate for the research question.

• Examine the data analysis and synthesis: Determine whether the data analysis and synthesis are appropriate and whether statistical methods are appropriate.

• Evaluate the conclusions: Determine whether the conclusions of the systematic review are supported by the evidence presented and whether the limitations of the systematic review are clearly stated.

Criteria	Questions to consider	Significance
Research question	Is the research question well-defined and clearly stated?	The research question should be specific, unambiguous, and relevant to the research topic.
Search strategy	Was the search strategy comprehensive and reproducible?	The search strategy should be comprehensive, reproducible, and include all relevant databases and sources.
Study selection	Was the study selection process unbiased and reproducible?	The study selection process should be transparent, reproducible, and based on predefined inclusion and exclusion criteria.
Quality assessment	Were the quality and risk of bias assessments appropriate and systematic?	Quality and risk of bias assessments should be appropriate, systematic, and based on predetermined criteria.
Data synthesis	Was the data synthesis appropriate and consistent with the research question?	The data synthesis should be appropriate, consistent with the research question, and include appropriate statistical methods.
Conclusion	Are the conclusions supported by the data presented and consistent with the research question?	The conclusions should be supported by the data presented and consistent with the research question.

Meta-analysis:

Meta-analysis involves the statistical combination of results from multiple studies to obtain a summary effect size. The Cochrane Collaboration provides a methodology for conducting meta-analyses in the health field. This methodology involves the use of a standardized approach to identify relevant studies, assess the quality of the included studies, extract data, and combine the results using appropriate statistical methods.

One of the main advantages of systematic reviews and meta-analysis is the ability to synthesize evidence from multiple studies, providing a higher level of evidence compared to individual studies. However, it is important to note that systematic reviews and meta-analyses are only as good as the quality of the studies included. Therefore, it is essential to critically appraise the quality of the included studies to ensure the validity and reliability of the results.

In summary, systematic reviews and meta-analyses are important tools for synthesizing evidence and providing a high-level overview of a particular research question. However, it is important to critically appraise the quality of the included studies to ensure the validity and reliability of the results.

References:

1. Moher, D., Cook, D. J., Eastwood, S., Olkin, I., Rennie, D., Stroup, D. F., & Altman, D. G. (1999). Improving the quality of reports of meta-analyses of randomized controlled trials: the QUOROM statement. The Lancet, 354(9193), 1896-1900.
2. Moher D, Liberati A, Tetzlaff J, Altman DG, PRISMA Group. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med. 2009 Jul 21;6(7):e1000097. doi: 10.1371/journal.pmed.1000097. PMID: 19621072.
3. Shea, B.J., Reeves, B.C., Wells, G., Thuku, M., Hamel, C., Moran, J., … & Tugwell, P. (2017). AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. BMJ, 358, j4008.