Systematic Reviews for the Health Sciences

A large portion of your systematic review will be spent in creating and gathering search terms (keywords and controlled vocabulary). This is a key part where librarian assistance can be extremely helpful.

Use the Yale MeSH analyzer to gather the medical subject headings of your gold standard articles. Results can be exported and analyzed so that you can choose appropriate medical subject headings.

During term harvesting gather terms from:

• Gold Standard Articles (especially from the title and abstracts)
• Medical Dictionary
• DynaMed Plus

Think about:

• Alternate spellings
• Acronyms
• Phrases

These tools can help determine frequency of terms:

Example: Asymptomatic Intracerebral Hemorrhage

• MESH: 
  • Cerebral Hemorrhage[Mesh]
• PubMed ENTRY TERMS: 
  • Cerebrum Hemorrhage*
  • Cerebral Parenchymal Hemorrhage*
  • Intracerebral Hemorrhage*
  • Cerebral Hemorrhage*
  • Cerebral Brain Hemorrhage*
• MESH Tree:
  • Basal Ganglia Hemorrhage
  • Putaminal Hemorrhage
  • Cerebral Hemorrhage, Traumatic
  • Cerebral Intraventricular Hemorrhage
• EMTREE:
  • 'brain hemorrhage'/exp
• Embase synonyms:
  • brain bleeding
  • brain haemorrhage
  • brain hemorrhage
  • brain microhaemorrhage
  • brain microhemorrhage
  • cerebral haemorrhage
  • cerebral hemorrhage
  • cerebral microbleed
  • corpus callosum bleeding
• Emtree Tree
  • brain ventricle hemorrhage
  • cerebellum hemorrhage
  • massive intracerebral hemorrhage
  • subarachnoid hemorrhage
• OTHER:
  • ICH
  • aICH
  • Asymptomatic
  • Non symptomatic
  • nonsymptomatic

  • symptomless 

  • symptom-less

Once you have gathered the controlled vocabulary, keywords, synonyms, and phrases - it is time to begin combining the terms to create a search string for one database. Key components for this include: Boolean operators, truncation, proximity searching, and wildcards.

1. AND - Narrows the search
   • Diabetes AND Nutrition
2. OR - Broadens the search
   • Infants OR Newborns
3. NOT - Narrows the search
   • Hearing loss NOT Hearing aids

• Truncation is used to search for multiple endings of a word and is typically indicated with an asterisk.
• For example: obes* will find obese and obesity

• Proximity Searching is a way to search multiple terms that appear within a certain number of words from each other. There are typically two options to use -- Near or Next (sometimes also called Within). Order does not matter with Near, meaning ice NEAR/1 cream will find ice cream and cream ice. Order does matter with Next, meaning ice NEXT/1 cream will only find ice cream. Use the table below to see how popular databases require proximity operators to be listed. (Replace x with a number to represent the amount of words present between your terms)

• There are a variety of wildcards that are available in different databases. They are similar to truncation but are used to stand for either a single letter or multiple letters within a word. They are indicated by a question mark or a hash mark (#) - check with the database you are using to determine which symbol is required.
• For example spelling variations of hemorrhage can be found with:
  • Web of Science: h$emorrhage
  • Scopus: h*morrhage

Once you have formatted your search string you need to test it to make sure that it finds your gold standard articles. If your search string does not find your GSAs you will need to make appropriate adjustments.

Unfortunately, there is not a magic search string format that will work in all databases. You will need to translate search string #1 that you have verified finds your gold standard articles. This includes potentially changing or removing:

• Controlled vocabulary
• Truncation & wildcard characters
• Proximity operators

There are quite a few tools and guidelines that can help you with this step: