How to do a systematic review –10 simple steps for beginners

Hello all, I know you are beginning to do a systematic review and looking for help to start. I am happy to help you in understanding each step and guide you in the process.

Systematic reviews can be overwhelming in the beginning, and most of the online modules or workshops are unable to simplify the steps of a systematic review. I was in the same situation a few years back, but I was lucky to have people in my team who helped me understand each step gradually.

As a personal experience, I would suggest you focus on one step at a time and not go through the entire method at once. It can be scary and frustrating. For the ease of understanding, I have simplified the 10 steps for conducting a systematic review. I recommend you NOT to do a systematic review alone. You need a minimum of two people to do a systematic review. I will give you the details within each step in upcoming blog posts. So let’s begin.

• Decide your amazing topic

Choose to do a review on a topic which fascinates you (otherwise the entire process can be extremely tedious). This would usually include searching the literature and finding the gaps in evidence. Once you have decided your topic go to PROSPERO (link) and search if a similar review is ongoing elsewhere. It is a good idea not to do the same review otherwise you will waste your energy duplicating the evidence.

• Develop your research question

If you have decided on a novel topic, then it’s time to write down your research question. This is a very important step. Think of questions which you want to answer at the end of your review. It is crucial to take expert advice either from your supervisors or senior colleagues.

• Write a protocol for your review

That’s right! Just like any other research, you first need to write down your protocol. Develop your PICO format, i.e., P=population, I=intervention, C=comparison, O=outcome

Also, decide the type of study designswhich you wish to include in your review. It can be a qualitative, observational or randomized controlled trial. Figure out the inclusion and exclusion criteria for including the studies in your review. This also requires some expert advice.

• Register in PROSPERO

Once you have finalized the protocol anddecided your team, then it’s time to register in PROSPERO. Registering in PROSPERO helps in two ways. Firstly, it gives transparency and rigor to your methodology. Secondly, it prevents other in conducting the review on the same topic.

• Build your search strategy

This is one of the most vital steps in a systematic review. Your search terms should encompass all relevant studies pertaining to your review question. You don’t want to miss out any relevant study because your search strategy was not good enough. If you are very new in building a search strategy, then you can even ask for help from your librarian. Otherwise, you need to find out a maximum number of terms which are required to retrieve all the studies. How to develop a detailed search strategy is a big topic in itself which we will learn later!

• Run the search in different databases

Now that you have the search strategy ready, you should start running the search in different databases. Databases will depend on which discipline you belong. For research in health sciences, databases like PubMed, COCHRANE, EMBASE, CINAHL, Web of Science, Clinical Key, Pedro are few examples. You should run the search in a minimum of three databases to be sure that you have not missed out relevant studies.

• Remove duplicates and start screening

Once you have run the search in all the databases and imported the files in your PC, then remove duplicates. You are likely to have many duplicate studies because you have searched multiple databases. You can either do it manually (difficult and time-consuming) or use software like Revan, Rayyan, Mendeley, Endnote, etc. Start screening the titles of all the studies for inclusion and exclusion. I will write a post on ‘How to screen the studies’ separately. 

• Extract your data

Now that you have screened the articles for title, abstract and full text, it’s time to develop a simple data extraction sheet or excel sheet. Start extracting the required information from the included studies like title, authors, year, journal, study design, number of participants, characteristics of participants, intervention, outcome measures and results including mean values and p-values.

• Decide if your review is suitable for performing a meta-analysis

If your data is homogenous (similar outcome measures and similar study participants) then you can think of performing a meta-analysis. You can take help of your statistician for meta-analysis or you can even DIY! A separatesession on it 😉

• Start writing your systematic review

As obvious, it is a huge topic to discuss. I will talk about a few essential points in writing a review. First, prepare a table of all the included studies. Then begin writing your methods section. Give details of how your search was conducted and how many articles did you finally include. Also, talk about how you have dealt with the risk of bias in the studies. Then start writing your results section. Summarize the findings of each study and interpret it. Write the risk of bias summary. Then write your discussion on what have you interpreted from your results. How is it different/similar from previous studies/reviews, how have you contributed to the existing knowledge, and what should be the future scope for conducting other studies. Last, write your introduction with convincing reasons for performing your systematic review.

That’s it! Go ahead and publish your fantastic review.