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Strategies for Searching the Literature Using PubMed

Course Number: 682

Structuring a PubMed Comprehensive Search Using a PICO Question

The first course, Evidence-Based Decision Making: Introduction and Formulating Good Clinical Questions,1 demonstrated how to construct a PICO Question from a case scenario. The following is a brief review of the case, the PICO question and key terms that will be used to illustrate a comprehensive PubMed search.

Case Scenario

Your new patient, Mr. Nathan Baker, is a 20-year old college student-athlete who has been swimming competitively since he was 12-years-old. His chief complaint is about the smooth, yellow areas near his gum line that he recently noticed. He wants to know what might be causing this and if there is anything he can do to fix and/or prevent it from getting worse. When reviewing his health history and behaviors, you learn that Nathan is a vegetarian, frequently snacking throughout the day on healthy fruits and vegetables. He also consumes sports drinks and an occasional energy drink with his hectic student/athlete schedule.

Nathan currently uses a manual toothbrush right after every meal, flosses nightly, and uses whatever fluoride toothpaste is on sale when he goes to buy one. Since you suspect his chief complaint is due to erosion, you perform the Basic Erosive Wear Examination (BEWE),2 and calculate his BEWE score to be 10, indicating he is at medium risk for erosive wear.

From Nathan’s assessment, we suspect the erosion is due to multiple risk factors including his diet and dietary habits, oral health regimen, and his competitive swimming. After discussing each of Nathan’s risk factors, he realizes that some of his habits are contributing to his oral health problem. He had always thought being a vegetarian was healthy and that it was good to brush right after meals. He did not know that his diet was acidic and eating too frequently could contribute to erosion.3,4 Nor did he realize that he should wait 1-2 hours before brushing his teeth after an acid exposure,5 or that as a competitive swimmer, if he is training in water with a pH lower than the optimal (7.2-8.0) he may be subject to further erosion.6

You both agree on changes that he can make with his eating and oral care habits but realize there are some things that aren’t going to change – like the fact he is a competitive swimmer and plans to remain a vegetarian. He then asks you about the toothpaste he should be using. He asks you about Sensodyne Pronamel® (a sodium fluoride toothpaste with potassium nitrate), since he recently heard a TV commercial stating that it helps with erosion. You typically recommend a stannous fluoride toothpaste, like Crest Pro-Health, but are not sure which one will be more effective in preventing the initiation and further progression of dental erosion.

To find the answer, you structure Nathan’s question following the PICO formula: "For a patient with erosive tooth wear (P), will Sensodyne Pronamel® (a sodium fluoride toothpaste with potassium nitrate) (I), as compared to Crest Pro Health (a stannous fluoride toothpaste) (C), be more effective in preventing the initiation of further erosive tooth wear (O)?"

Key search terms are derived from the PICO components comprising the PICO question. In this case, they include the Intervention (I: sodium fluoride toothpaste with potassium nitrate or Sensodyne Pronamel), and the Comparison (C: stannous fluoride toothpaste or Crest Pro-Health toothpaste). In this specific example, including the Problem (P), erosive tooth wear, as part of the search will be important since the two different fluoride toothpastes may be compared for other reasons, e.g., occlusal or root caries, or dentinal hypersensitivity. Without including the P, which narrows the search to the specific problem, the search would include different answers/outcomes other than their comparison for tooth erosion. However, in general, the two main search terms are the I and C since you will want studies that compare the two to determine which is more effective. Next, identify any additional terms or phrases (synonyms) related to the already identified P, I, C, and O (See Table 1 – Mr. Baker’s PICO Worksheet). By generating these words, alternative key terms are identified that facilitate finding evidence to answer the question.

ce682 - Images - Table 1.

Table 1. Completed PICO Worksheet for Mr. Baker’s Case.1