Medicine Subject Guides: Literature search

Developing a well-structured search statement is crucial for conducting effective literature searches. Here are some steps to help you develop a search statement:

1. Translating research questions into question formation framework: Question formation framework such as PICO, SPICE, and SPIDER, allows for a systematic approach to investigate the research question and search for relevant evidence. By breaking down the research question into components, you can clearly define their inquiry and guide their analysis of findings. 
 
2. Identify the main concepts: Start by identifying the key concepts or main elements of your research question or topic. Break down your research question into its fundamental components (usually 2-3 components). 
 
3. Generate a list of relevant keywords: Generate a collection of relevant keywords and their synonyms for each concept. Take into account various variations, spellings, and terminology commonly used by researchers. When appropriate, incorporate subject headings or controlled vocabulary terms specific to your research field. 
 
4. Combine the keywords with Boolean operators: Use Boolean operators (such as AND, OR, NOT) to connect and combine your keywords effectively. AND narrows the search by requiring both terms to be present, OR broadens the search by including any of the terms, and NOT excludes terms from the search. 
 
5. Consider search modifiers: Consider additional search modifiers that can help refine your search. These modifiers might involve specific study designs, date limitations, geographical locations, or population characteristics. Include these modifiers in your search statement as needed to enhance the precision and relevance of your search results. 
 
6. Use truncation and wildcards: Use truncation symbols (typically) or wildcards (such as ? or *) to account for different word endings or spellings. For example, exercis* would capture exercise, exercising, exercises, etc. 
 
7. Structure the search statement: Combine the concepts, keywords, Boolean operators, and search modifiers into a well-structured search statement. Use parentheses to group related terms and clarify the search logic. For example: (exercise OR physical activity) AND (depression OR depressive disorder) AND (older adults OR elderly) 
 
8. Adapt the search statement for different databases: While the core search statement may remain the same, you may need to adapt it to fit the specific syntax and indexing conventions of different databases. Consult the help or search guides provided by each database for guidance. 
 
9. Refine and iterate the search statement: As you conduct initial searches and review search results, refine and iterate your search statement. Add or remove keywords, adjust the Boolean operators, or modify search modifiers to achieve the desired balance of relevance and comprehensiveness. 
 

To ensure transparency and reproducibility, document your search strategy, including the initial search statement and any modifications. Include the search statement when registering the protocol to provide a clear record of the search terms and strategies used. This promotes transparency and facilitates replication of your search process.

A MeSH term, short for Medical Subject Heading, is a standardized vocabulary employed by the National Library of Medicine (NLM) to classify and index biomedical literature. MeSH terms are assigned to articles and resources, such as those found in PubMed, to ensure consistent organization and categorization. They represent specific concepts, diseases, treatments, or other subjects within the medical and healthcare field. MeSH terms aid in refining literature searches, improving accuracy, and streamlining the retrieval of relevant articles. Researchers utilize MeSH terms to locate articles pertaining to specific topics and enhance the precision of their searches.

You may find MeSH term through Pubmed homepage:

Grey literature refers to a diverse range of documents generated by various entities such as government, academia, business, and industry. These documents exist in both print and electronic formats and are protected by intellectual property rights. While they possess enough quality to be collected and preserved by libraries and institutional repositories, they are not published by commercial publishers. In other words, the producing bodies of grey literature prioritize activities other than publishing as their primary focus. Examples of grey literature include:  Conference abstracts, presentations, proceedings; regulatory data; unpublished trial data; government publications; reports (such as white papers, working papers, internal documentation); dissertations/theses; patents; and policies & procedures. Gaining access to grey literature for a systematic review can be challenging as it is not typically indexed in conventional academic databases. However, there are several approaches you can use: Explore specialized databases Contact experts and organizations Search conference proceedings Scan institutional repositories Conduct targeted web searches Utilize social media and professional networks Hand-search relevant sources.

Here are a few websites that can be useful for searching grey literature:

1. Theses and Dissertations:

   HKU Thesis Online
   HKU Thesis Online is an electronic repository that provides access to theses and dissertations submitted by HKU students. It offers a centralized platform for users to browse and download research works from various disciplines.

   ProQuest Dissertations and Theses
   ProQuest Dissertations and Theses is a database that provides access to a vast collection of dissertations, theses, and other unpublished research from universities worldwide. It can be a valuable source of grey literature.

   For more:Please refer to HKU library

2. Clinical Trials:

   CENTRAL (Cochrane Central Registrar of controlled Trials)
   CENTRAL (Cochrane Central Register of Controlled Trials) is a database that houses a wide range of clinical trial reports. It is a key component of the Cochrane Library, providing researchers and healthcare professionals with access to a vast collection of published and unpublished controlled trials. Researchers rely on CENTRAL to obtain high-quality evidence for their systematic reviews and meta-analyses, aiding in evidence-based decision-making in healthcare.

   ClinicalTrials.gov
   ClinicalTrials.gov is an online database that provides information about clinical trials from around the world. It is maintained by the United States National Library of Medicine (NLM) and the National Institutes of Health (NIH). The database allows users to search for and access information about ongoing and completed clinical trials, making it a valuable resource for researchers, healthcare professionals, and the general public.

   ISRCTN registry
   The ISRCTN registry is an online database that serves as a platform for the registration and tracking of clinical trials worldwide. It is recognized by the World Health Organization (WHO) and the International Committee of Medical Journal Editors (ICMJE) as a primary clinical trial registry. The ISRCTN registry provides researchers with a unique identification number for their trial and aims to promote transparency and accountability in clinical research.

3. Other Online Sources

   OpenGrey
   OpenGrey is a multidisciplinary database that provides access to grey literature produced in Europe. It includes reports, theses, conference papers, and other types of grey literature.

   Grey Literature Report
   Grey Literature Report is a repository that aggregates grey literature from various disciplines. It offers access to technical reports, working papers, government documents, and more.

   WorldWideScience
   WorldWideScience is a global science gateway that allows you to search grey literature as well as scientific literature from multiple countries and international organizations.

   BASE (Bielefeld Academic Search Engine)
   BASE is one of the world's largest search engines for academic open access web resources. It includes grey literature sources such as institutional repositories, digital libraries, and conference papers.