This guide aims to round up the most frequently asked questions (FAQs) on conducting systematic reviews
Systematic review and meta-analysis are not interchangeable.
Systematic review is a rigorous process, which takes time.
Whereas, meta-analysis is a statistical technique to combine numerical data from multiple studies. Meta-analysis may include all the studies identified in a systematic review or may include only a few of those studies. Meta-analysis is a quantitative summary of the study results. You may find systematic reviews without meta-analysis, and also you may find systematic reviews with meta-analyses. Meta-analyses may be conducted on their own, but this is rare. However, you can find some papers which do include meta-analysis in their titles.
Meta-analysis is a statistical approach to produce a summary estimate from relevant studies. The outcomes of meta-analysis help researchers/health professionals/policymakers/patients understand a summary effect of an intervention, for instance, which is useful to develop guidelines which have a direct impact on patient care.
There are several useful handbooks and interactive training available supported by the Cochrane Collaboration group.
Cochrane meta-analysis handbook
It is very important to take some time to think about whether a meta-analysis would be appropriate for your project. For instance, if the included studies show high heterogeneity in terms of population, study design, and outcomes. If the study designs are too different and then you cannot do a meta-analysis.
There are some critics of the biases. In general, clinical trials with negative results are unlikely to be published. Therefore, meta-analysis needs to do a better job of including those unpublished results. Low-quality studies could add limitations to meta-analysis. There was also the issue of sometimes including small studies double counting where the same trials were published in different papers.
Therefore, in this case, you can do a narrative synthesis (or qualitative synthesis) to narratively summarise the findings of the synthesis.
