The first search question you should ask, if you plan to do a systematic review is, "has anyone done this before"? The Cochrane database of systematic reviews can be used to search for reviews conducted by the Cochrane collaboration. You can also search for review protocols for the Cochrane reviews. You can also search PubMed for systematic reviews. For example, I'm doing a search in PubMed for Mediterranean diet and metabolic syndrome. To limit my search results to systematic reviews, I am going to first change the filter display settings in PubMed to show the systematic review filter, and then limit my search results to that. I can see that there are this many articles indexed in PubMed on this topic which are considered to be systematic reviews. Or you can just do a clinical query search in PubMed, and the systematic reviews will be listed in the middle column here. To see all of them, click "See all". So, either way you get to the same list of systematic reviews. As you can see, it is unlikely that you would find an overwhelming number of systematic reviews on your topic, because they are usually time consuming to do. The key is to not miss any. So instead of a simple keyword search in the database mentioned above, you might also want to consider searching with the various synonyms of your keywords and with controlled vocabulary terms such as the Medical Subject Headings in those systems that support them, such as PubMed. And because it is time consuming to do systematic reviews, it is highly probably that another team of reviewers is currently working on a project similar to yours. So you will need to constantly monitor the publication of new reviews. It is a good idea to sign up for the various alerting services with databases such as Cochrane or PubMed, so that you are alerted of any possible similar reviews that are published prior to yours. Prospero is a database of prospectively registered systematic reviews. According to the "About Us" page, the key features from the registered review protocols are recorded and maintained as a permanent record. In other words, those who chose to register their review protocols here do that at the inception of their projects, and not after the reviews are published. This will help you find potential ongoing review efforts that are on a similar topic to yours. I would also recommend that you also register your review protocols here, so that efforts are not duplicated elsewhere. Now even if you are able to find existing systematic reviews on your topic, this does not automatically invalidate your project. The existing review may not be conclusive... they may be limited to a specific age group, ethic group, or geographical region... They may have been done a decade ago, and things have changed since then. All of these make it worthwhile for you to redo the review, either from a different perspective or with a new different set of primary studies. The next search question you should ask is "are there enough primary studies on my topic for me to review, and draw a meaningful conclusion from? Are there hundreds of them, or are there only a handful of them"? If there are not enough qualified primary studies for you to review, you may not want to continue with your project. To answer these questions, a "scoping search" is usually performed before full-scale searches. As the name implies, a scoping search is a preliminary search conducted for the purpose of finding the scope of existing literature on your topic. You should do this in databases that are most likely to include articles on your topic. Databases such as PubMed are good starting points for scoping searches on biomedical topics. The benefits of a scoping search are many - you will not only get a rough idea of how many primary studies are out there that might be included in your review, you will also learn to better describe your topic with the terms you find in your scoping search. You may come across terms, or their synonyms, that you have never thought of. This is a good opportunity to develop your list of search terms for your full-scale search later on. Another way to get a sense of the scope of your topic, and to develop your list of search terms, is known as "pearl growing", which usually starts with a number of key studies on your review topic. The identification of key studies would depend on your knowledge and experience level. If you are an expert in the field, chances are that you already know the key studies, and who the key authors are. If you're not, you should have an expert in the field direct you to those key studies and authors. Once you have these key studies, the "pearls", you will be able to find other closely related studies using techniques such as citation analysis, which we will cover in a later video. You will also be able to find the most commonly used terms in these studies for the concepts in your topic. Identifying these key studies has many added benefits. They can be use to validate and verify your search at the end of your search process. Does your search strategy sucessfully include all the key studies and authors. We will discuss how you verify and validate your search in a later video. Once you have a list of terms you can use in your full-scale search, it is useful to organize them in a way that helps you do the search. Normally you'll first group them according to your PICO model, and then you try to separate controlled vocabulary terms from free text keywords, terms, and their synonyms. Once your search terms are in a concept table like this, it is a lot easier to construct a search query in most databases. For example, I can construct a search for my first concept in Ovid MEDLINE, like this. Basically I'm running a search with the medical subject heading for the concept, and a series of synonymous keywords strung together with the Boolean "or". I will go over specific search query syntax in a later tutorial. Okay, now you have your search terms, but you still have to decide where to search. There are dozens of databases out there that might be relevant to your topic. Which ones to search really depends on what your topic is. For example, we talked about cross-disciplinary topics, such as this one here with an educational aspect. In which case, a search in the education database is required. In the next few screens, I'm going to go over some commonly used databases for different subject areas, which hopefully will help you which ones to use for your project. First of all, there are couple of core biomedical databases, such as MEDLINE (either via Ovid or PubMed), Embase, Scopus, and the Web of Science - which is part of Web of Knowledge. These products contain a significant amount of bibliographic references on biomatical subjects, and should always be considered if your topic is a biomedical one. Reviewers typically also use Google Scholar in their searches, and report the search results in their reviews. Google Scholar usually produces good useful results, especially in gray literature searches and citation analyses. However, one must be aware that Google Scholar searches are not as transparent and reproducible as systematic reviews typically require, because we don't know what exactly is searched and how exactly the search is run. Another person who runs exactly the same search at a different time, may end up with very different results. Additionally, unlike the other bibliographic databases, Google Scholar searches almost always return a large number of results, making it difficult for reviewers to evaluate all of them. There are also a lot of databases with a focus on clinical content, such as these here, which I would recommend if your topic is clinical in nature. And here is an example list of databases you can search if your topic is related to global health or public health. These are databases for social sciences--notice our education database example is here. I mentioned citation analysis previously--Scopus, the Web of Science, and Google Scholar are essential tools for doing citation analyses. If you're not sure which databases to search, and what subject areas the databases cover, there are also tools to help you with that. But I would recommend talking to your librarians, or other information professionals, trained to perform systematic reviews in that case. So this is a table you can use to help you and your team keep track of your project. On the left, is the question for your project - usually in the PICO format. Then you have a series of databases in different subject categories that you've decided to search for your project. As we mentioned in previous tutorials, you will also need to search gray literature for any unpublished materials - we'll cover that in a later tutorial. Also, as we've mentioned previously, you should search specifically for studies with the best methodological design. Tools such as validated methodological hedges are available to help you with that. We'll cover more of that later in these tutorials. You might also want to record here some commonly agreed upon limits that you want to apply to all your searches in the databases, just so that all your team members are aware of them. Now that you've done your scoping search, familiarized yourself with your topic, and you know that you have enough qualified primary studies to work with. You have a list of terms you can search with, and you know which databases to search. You're now ready to run your search, which we will cover in our next video. Thanks for watching - I'll see you next time.