Evidence Based Medicine

STEP 2: SEARCH EFFICIENTLY FOR RELEVANT RESEARCH

Precise Searching Techniques

In Evidence-based Medicine, the goal is to search efficiently and precisely for the evidence to answer your clinical Foreground question. You will find fewer results, but more relevant ones. The PICO Form allows you to quickly gather the crucial, relevant keywords that describe your clinical question. PICO Form (.doc file)

Using the following example of a PICO form:

P: 10 year-old male with mild persistent asthma

I: Cromolyn 4 times/day

C: Montelukast once/day

O: Reduce asthma attack frequency

The relevant keywords for searching for research articles in this case would be:

Male child, mild asthma, cromolyn, montelukast

Combined these into a search query using Boolean connectors, we get:

(Male AND child) AND (mild AND asthma) AND cromolyn AND montelukast

Running that search on PubMed found the following results:

It turns out that all 3 of the articles found above help answer the clinical question – so this search had 100% precision! High precision searching is one goal of Evidence-Based Practice.

However, if you do not get any results, then you will have to search again using fewer of the specific details from your PICO form, until you obtain a relatively small number of relevant results.

An example of how one could remove specific details from the search terms above in order to create a slightly broader search is:

(child AND asthma) AND cromolyn AND montelukast

As you can see, the specific details of the child’s gender and the severity of the asthma have been removed. This search brings back about 20 results.

STEP 3: EVALUATE FOUND RESEARCH ARTICLES FOR INTERNAL & EXTERNAL VALIDITY

Evaluating Research Articles Using Critical Appraisal Checklists

In Evidence-Based Practice, evidence (consisting of articles describing research studies) needs to be appraised by anyone who wishes to use that evidence to formulate a decision. However, not every researcher or clinician is an expert in clinical study design.

Fortunately, checklists are available which make it easier to quickly double-check an article’s internal and external validity.

Critical Appraisal Checklists

Formulated by the University of Glasgow (downloadable .doc files)

• Decision Analysis
• Diagnosis
• Economic Evaluation
• Educational
• Guidelines
• Harm
• Prognosis
• Qualitative Research
• Systematic Review
• Therapy

Each checklist will ask several questions about elements that are (or should be) found in a well-done research study. This will include questions about a study’s internal validity (i.e., Was the study designed and carried out correctly?) as well as questions about the study’s external validity (i.e., Is the population who participated in the study similar enough to the patient(s) or population you are now asking a question about for it to be worth your time to read the article and take its conclusions into account as you make a decision?).

In general, the more “yes” answers are on your checklist, the more likely it is that the article describing a particular research study is worth your time to read. In the end, each researcher or clinician must make a judgment call regarding which articles – and evidence – to consider.

STEP 4: ETHICALLY UTILIZE THE EVIDENCE

• When answering a clinical question, patient preference must be taken into consideration
• Proper attribution (citations) must be given for the information used

STEP 5: REFLECT UPON THE PROCESS

• Reflect upon what part(s) of the process worked well versus what was more challenging
• Reflect upon the utilization of the information gained during the process