Medical Residents: EBM Review and Practice

Provides general clinical search examples for practicing the EBM steps related to asking clinical questions and acquiring evidence.

Patient Scenario

For an adult male, does a lower sodium diet or lower reduced salt intake reduce hypertension?

PICOTT Analysis of the Clinical Question

Patient / Problem Adult Male with Hypertension
Intervention Low Salt Diet or Reduced Sodium Intake
Comparison No change in diet or salt intake
Outcome Lower Blood Pressure or Reduction in Hypertension
Type of Question Therapy
Type of Study Systematic Review of RCTs > individual RCTs > cohort studies

PICOTT to Search

Select words from the PICOTT concepts to guide the development of a PubMed search. Remember:

  • Start with key concepts. You do not need to use all of the concepts or all the words.
  • Gender and specific age limits are usually added after a preliminary search unless they are central to the clinical question.
  • Consider alternate word endings, especially for key concepts.
  • Consider synonyms.
  • Use an OR to combine alternate word endings and enclose the set of similar words in parentheses.
Question Search Terms
Adult Male With Hypertension (adult AND male)
  AND
Hypertension

(hypertension OR "high blood pressure")

  AND
Salt Intake

(salt OR "sodium chloride")

  AND
Study design filters Systematic Review of RCTs > individual RCTs > cohort studies

 

Preliminary search:
(adult AND male) AND (hypertension OR "high blood pressure") AND (salt OR "sodium chloride")

Try running this search (cut and paste search terms above) in Pubmed.    Look at the results of this search. 

Evaluate the Search

Run the search in PubMed:

  • On 05/15/2015, this search found 3578 articles, which is way too many articles to look at for this search.. 
  • How do we narrow our results for this search?

Check the Search Details:

(("adult"[MeSH Terms] OR "adult"[All Fields]) AND ("male"[MeSH Terms] OR "male"[All Fields])) AND (("hypertension"[MeSH Terms] OR "hypertension"[All Fields]) OR "high blood pressure"[All Fields]) AND (("sodium chloride"[MeSH Terms] OR ("sodium"[All Fields] AND "chloride"[All Fields]) OR "sodium chloride"[All Fields] OR "salt"[All Fields]) OR "sodium chloride"[All Fields])

  • Look for terms that did not map to a MeSH term, or did not map effectively to a MeSH Term.

Revise the Search:

  • Try limiting by Type of Article, looking for Systematic Review or Meta-Analyses.
  1. Use the Article Type filter(on the left hand side of the Pubmed record)to see if there are Meta-Analysis or Systematic Reviews to limit your results.   There are now 40 results.
    • Search details: (("adult"[MeSH Terms] OR "adult"[All Fields]) AND ("male"[MeSH Terms] OR "male"[All Fields])) AND (("hypertension"[MeSH Terms] OR "hypertension"[All Fields]) OR "high blood pressure"[All Fields]) AND (("sodium chloride"[MeSH Terms] OR ("sodium"[All Fields] AND "chloride"[All Fields]) OR "sodium chloride"[All Fields] OR "salt"[All Fields]) OR "sodium chloride"[All Fields]) AND (Meta-Analysis[ptyp] OR systematic[sb])                                                                                                                                
  2. Try using Clinical Queries/Systematic Reviews to find additional articles.   Click here to search Pubmed using the Clinical Queries/Systematic Review filter.
  • Search details are:  systematic[sb] AND ((("adult"[MeSH Terms] OR "adult"[All Fields]) AND ("male"[MeSH Terms] OR "male"[All Fields])) AND (("hypertension"[MeSH Terms] OR "hypertension"[All Fields]) OR "high blood pressure"[All Fields]) AND (("sodium chloride"[MeSH Terms] OR ("sodium"[All Fields] AND "chloride"[All Fields]) OR "sodium chloride"[All Fields] OR "salt"[All Fields]) OR "sodium chloride"[All Fields])) AND (Meta-Analysis[ptyp] OR systematic[sb])
  • This search found 40 articles, the same as limiting the search by publication type.     Notice how Pubmed Clinical Queries added terms to our search strategy. 

Review the Results:

  • You notice that all of the 40 articles in this set are Meta-Analyses OR Systematic Reviews.  Are these results relevant?
  • What if we took out "male" terms, and searched for just Adult????  Would that change our results?
  • The results went from 40 to 67 when we deleted Male from the search..  Let's look at some of the results.
  • Here is a systematic review from the search results.    Adler AJ, Taylor F, Martin N, Gottlieb S, Taylor RS, Ebrahim S. Reduced dietary salt for the prevention of cardiovascular disease. Cochrane Database Syst Rev. 2014 Dec  18;12:CD009217. doi: 10.1002/14651858.CD009217.pub3. Review. PubMed PMID: 25519688. 
  • And here is another result:  Kwan MW, Wong MC, Wang HH, Liu KQ, Lee CL, Yan BP, Yu CM, Griffiths SM. Compliance with the Dietary Approaches to Stop Hypertension (DASH) diet: a systematic review. PLoS One. 2013 Oct 30;8(10):e78412. doi: 10.1371/journal.pone.0078412. eCollection 2013. PubMed PMID: 24205227; PubMed Central PMCID: PMC3813594.
  • With the previous article, should we add the term "dash OR "Dietary approaches to stop hypertension" to our search to increase the results?   Let's add these two terms to the salt terms and see if it increases our search results.  
  • When adding those two search terms to our search, it did not increase our results for meta-analyses or systematic reviews.   So we still have results of 67 to review.
  • Here is one more article to review:  Matyas E, Jeitler K, Horvath K, Semlitsch T, Hemkens LG, Pignitter N,Siebenhofer A. Benefit assessment of salt reduction in patients with hypertension: systematic overview. J Hypertens. 2011 May;29(5):821-8. doi: 10.1097/HJH.0b013e3283442840. Review. PubMed PMID: 21475042.         
  • What about adding MeSH (medical subject headings) to increase our results?   If you search in MeSH for subject headings related to dietary salt, the subject headings of diet, sodium-restricted[mesh] OR sodium chloride, dietary[mesh] are found.    Let's add those two terms to our search strategy and see if we get more relevant results:
    • adult AND (salt OR "sodium chloride" OR diet, sodium-restricted[mesh] OR sodium chloride, dietary[mesh]) AND (hypertension OR "high blood pressure") 
  • Results increased to 76, which is a reasonable number of results for this search for systematic reviews or meta-analyses.

End the Search:

This patient scenario is an example of a clinical question where there appears to be evidence that is specifically relevant to the clinical question we asked. 

 

 

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