Secondary research – the basics of narrative reviews, systematic reviews, and meta-analysis

Secondary research – the basics of narrative reviews, systematic reviews, and meta-analysis

When it comes to academic publishing, typically, researchers think of publishing original articles, which form the bulk of primary research articles. Research can also be published by summarizing, collating, or analyzing existing research data. Research that falls into this category is somewhat less common than primary research publications and is called secondary research. 

In secondary research publications, field observations that have been published by other authors are re-interpreted and re-written as a secondary research article. Let us now look at secondary publications in more detail. 

Why secondary research publications are important

Secondary research publications provide a different perspective or an additional analysis of the current literature. This can help identify gaps in the current knowledge in a field and highlight future directions. Secondary research publications include narrative reviews, systematic reviews, or meta-analysis.

Since no new data is required for such publications, often, they may offer early career researchers a chance to begin publishing. In addition, they are also important for busy scientists to remain up-to-date in their fields.

Digging deeper into secondary research publications

So what exactly is a narrative review, a systematic review, or a meta-analysis? And how does one go about writing them? Read on to learn more about these secondary research article types.

1. Narrative reviews

These reviews typically provide an overview of the current knowledge in a given field or topic. They are written with the idea of summarizing what is known and highlighting either new perspectives in the field, or drawing out pending questions that are yet to be unanswered. There is no new analysis in these reviews and depending on the topic, may be quite exhaustive, with a long list of references. Most journals allow for longer review articles – even longer than original primary research articles–often ranging from 5000-10000 words.

Narrative reviews typically include:

  • an abstract to summarize the article,
  • an introduction to provide a background on the topic and to detail why such a review is required,
  • a main text section that may be broken down to smaller sub-parts to discuss different aspects in the field,
  • a conclusion section to highlight the gaps and future directions,
  • and a detailed reference list.

Since the pre-existing knowledge in the field might be quite extensive, and multiple similar review articles may already have been published, it is very important to consider the scope and novelty of the topic to be covered before starting to write the review.

Also, it is highly recommended that authors contact the editors of suitable target journals prior to starting to write such reviews. This is to ensure that the editor would indeed consider the review article as many journals publish only solicited review articles.

2. Systematic reviews

Systematic reviews are more detailed and rigorous, and review a well-defined research question rather than a field or topic as in narrative reviews. Systematic reviews follow a systematic and reproducible methodology for searching all previous publications that have addressed the same question, and for critically assessing and analyzing the results from these previous publications in a review format.

Systematic reviews can be qualitative or quantitative. Qualitative systematic reviews derive data from descriptive or qualitative results, whereas quantitative systematic reviews include studies with numerical data.

Systematic reviews are structured in the typical IMRAD structure as are primary research articles, in which an abstract is followed by the main test including introduction, methods, results, and discussion and conclusions, followed by a reference list.

3. Meta-analysis 

Meta-analysis is a type of systematic review, but a systematic review in which statistical analysis is carried out to compare previously published studies and derive new interpretations or new findings. These are immensely helpful to understand the global effects of a particular finding rather than depending on the results of a single, isolated study in a particular region.

Meta-analysis may be considered more reliable than primary research as they include all the previously published data on the same research question and discuss the differences in study outcomes and the reasons behind them. They are becoming very popular especially in cases where a lot of individual and smaller studies have already been performed.

For instance, there may be several different studies on the effect of treatment A for colon cancer. These maybe case studies in random cities where a particular treatment plan was effective or smaller studies claiming the benefits of the same treatment plan. In a meta-analysis, all these published studies are analyzed together to determine the global effectiveness of treatment A.

Like systematic reviews, they also follow the IMRAD structure and are written as regular research articles. Many journals consider meta-analysis articles as original articles due to the statistical analysis performed and the subsequent new data gathered.

Guidelines for authors planning to write secondary research publications

If you are considering working on systematic reviews and meta-analysis, you need to keep a few additional points in mind: Like any primary research, systematic reviews and meta-analysis also need a protocol for the methodology. Such protocols can be published in a similar manner as done in case of primary research articles.

In addition, like primary research, journals request that a checklist be followed while writing the manuscripts. For systematic reviews and meta-analysis, you should follow the PRISMA checklist. Some journals may even request the protocol and completed checklist to be submitted along with the manuscript during submission to the journal.

Further, since the research involved needs to be exhaustive, and there is no point in duplicating similar secondary research, it is recommended that potential systematic studies be registered in a common registry, just like clinical trials are required to be registered. Registering is beneficial in holding stake for the study and preventing another group from working on the same topic. Multiple registries are available for registering your systematic reviews and meta-analysis. For instance, PROSPERO is a well-documented, open registry for all systematic reviews.

As you can see, all the above types of publications can be completed without any infrastructure, experimental setup, or large expenses. Thus, secondary research may also be referred to ‘desk research,’ as it can be completely carried out by sitting at a desk.

A major benefit of performing secondary research is its cost-effectiveness and shorter time frames. Primary research can lead to huge expenses depending on the type of experimentation and surveys done to gather data. In case of secondary research, data has already been collected and stored during primary research, making it more economic.

In addition to reviews, systematic reviews and meta-analysis, smaller articles such as perspectives, opinion articles, or commentaries are also secondary research and may provide an outlet to get your ideas and hypotheses out before you are able to implement the research.

So consider your options to progress your research career as there are several opportunities to publish even while you may be facing dipping funds or may be in a difficult position to carry out primary research!

 

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