How to search PubMed

Question type or domain

Every searchable clinical question falls into a category known as the "type of question" (or domain). Each question type is associated with specific research methods and designs, understanding the question helps identify the research methods and designs you want for your filter. There are many types of questions, in health the main ones are:

• therapy
• diagnosis
• prognosis
• etiology
• feeling/experience (qualitative studies)

The following are basic filters or hedges which can be used for evidence-based searching:

• Therapy: 
  “randomized controlled trial” OR “clinical trial” OR (double AND blind*) OR random* OR placebo*
• Diagnosis: 
  (sensitivity AND specificity) OR diagnosis OR “diagnostic use” OR (predictive AND value*) OR reliability OR validity 
• Prognosis: 
  incidence OR mortality OR “follow-up studies” OR prognos* OR predict* OR course 
• Etiology: 
  “cohort studies” OR risk OR (odds AND ratio*) OR (relative AND risk*) OR (case AND control*)
• Qualitative: 
  ethnography OR phenomenology OR grounded theory OR focus group OR narratology OR qualitative research OR "case study" OR participatory action research

To use these hedges requires a basic understanding of:

To use a hedge in PubMed:

1. Search PubMed and get your final results.
2. Copy and search the appropriate hedge.
3. Click Advanced (link; below search box)
4. Combine your search with the hedge using AND.  

Learn how to combine your searches in PubMed: