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Guided Medline Exercise: 7. Combine All Concepts

7.  Combine all Concepts

In Steps 2-7, we performed a separate Subject Heading and Keyword search for each PICO element: Population/Problem, Intervention, Outcome

Now, we will join our previous searches with the operator AND

Step by Step: Combine all Concepts

Combine all Concepts

Start in your Medline Search History:

  1. Note: you may need to Expand your Search History by clicking the Expand button to see all of your previous searches
  2. Identify the Population/Problem (3), Intervention(6) and Outcome(9) combined searches
  3. Start by combining Population/Problem and Intervention
    • Select the checkbox next to 
      • 1 or 2 (Population/Problem)
      • 4 or 5 (Intervention)
    • Combine with AND
  4. You now have a new combined search for Population/Problem and Intervention on line 10
  5. Finally add the Outcome to your new combined search (combining all PICO concepts)
    • Select the checkbox next to 
      • 3 and 6 (Population/Problem + Intervention)
      • 7 or 8 (Outcome)
    • Combine with AND
  6. The combined PICO concept search is shown in the Search History
Video Demo: Combine all concepts

Combine all Concepts

1. Using steps 1-6 above, combine your searches.


  • Your search may have more lines of search terms for each aspect of your topic
    • Follow this logic:
      • All sets for the first concept are combined with OR
      • All sets for the second concept are combined with OR
      • These 2 resulting sets are combined with AND
      • Combine the sets for the third concept with OR
      • Then combine this result with the previous result with AND
  • The number of results after combining just 2 sets with AND may be small,
    • STOP and review the results
    • Also, consider combining just the P, or first, concept and the O, or third, concept with AND.

2. Review the results