The Systematic Review Meta-Analysis Conundrum.

It is interesting to see a large number of systematic reviews and meta-analyses being done and uploaded for publication. Unfortunately, this sudden surge in publications has made the reviewer's and editor's jobs more challenging when it comes to processing systematic reviews.

I feel that such a deluge of systematic reviews and meta-analyses has resulted in a compromise in quality as far as following the protocols is concerned with any combination or strategy being used and in turn undermining the research. This write-up brings out the do's and don’ts and a few suggestions that can help understand Systematic reviews and Meta-Analyses simply.

Most importantly, a Systematic review is different than a Meta-analysis and should nowhere be considered to be the same. Littell et al.[1] in their book have brought out this difference explicitly and explained in detail the steps for the same.

When it comes to research analysis, it is the evidence that plays a major role in deciding the quality.[2] Meta-Analysis is the top-ranked followed, by Systematic review, Randomized control trial, Cohort studies, Case–control studies, Case reports, and Animal research and laboratory studies in a descending order [Table 1].

Table 1

Evidence hierarchy

1	Meta-analysis
2	Systematic review
3	Randomized control trial
4	Cohort studies
5	Case–control studies
6	Case series/case reports
7	Animal research/laboratory studies

Systematic reviews have a search question, are more detailed and involve a search strategy.[3] They require a lot of planning, are comprehensive, and reduce all risks of bias making the outcome more specific and sensitive to a particular topic. A narrative review, on the other hand, though descriptive and informative, can have an amount of selection bias. Most often, the systematic review has a meta-analysis component where the data are further processed, quantified, and summarized.

Muka et al.[4] have simplified the methodology to help synthesize the research data and publish the same successfully. Table 2 outlines the steps one needs to follow carefully each step, which is further subdivided to simplify the researcher's work.

Table 2

Steps for a systematic review

Step 1	Identify the research question
Step 2	Define the inclusion and exclusion criteria
Step 3	Search for studies
Step 4	Select studies
Step 5	Extract data
Step 6	Assess quality
Step 7	Synthesize and present results

The National Institute for Health Research has an international database named PROSPERO where all the prospective systematic reviews need to be registered. Once the protocol is registered on PROSPERO, the researcher gets a unique id number with all the details for future reference. It is interesting to note that details of Cochrane protocols get automatically loaded on PROSPERO.

There are various guidelines available for reporting particular type of studies. Use of these checklists and tools is important for a successful outcome.[5]

QUOROM: The Quality of Reporting of Meta-analysis[6]

CONSORT: Consolidated Standards of Reporting Trials[7]

PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses[8]

PRISMA P: Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols[9]

MOOSE: The Meta-analysis of Observational Studies in Epidemiology[10]

ROBINS-I: Risk of Bias in Nonrandomized Studies of Interventions[11]

ROB 2: COCHRANE: Risk of Bias tool for randomized control trials.[12]

We at the Journal of Conservative Dentistry urge the researchers to use the various tools available and improve the quality of their research. Adapting the various tools and adhering strictly to the criteria will only help bring out better and high-quality research papers.