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Evidence-Based Medicine Library Guide: Search strategy

Finding the Evidence in the Practice of Evidence-Based Healthcare

ASK the right question

The first step in the process of EBM is to formulate an answerable clinical question. Do not start looking for infomation on a general topic like diabetes or cardiovascular disease. Rather have a question that is specific and that attempts to answer a particlular problem or condition, e.g.

Question: In populations with a high prevalence of HIV infection, how effective is male circumcision for reducing HIV acquisition in heterosexual men?

PICO video

Types of questions ---> Types of studies

The type of question asked will determine the type of study that must be found to answer that question:

Therapy                                           Systematic reviews, RCT, meta-analyses                                                                                                                                    

Diagnosis                                        cross-sectional, validation studies

Prognosis                                       cohort, case control, case series

Aetiology/harm (causes, risk)        case control, cross sectional, RCT, cohort studies

Prevention                                     RCT, cohort studies                                                        

Quality improvement                    RCT

Qualitative                                   client, carer, family or community experiences

Study designs

PRESS: Peer Review of Electronic Search Strategies


Once an assessment of the patient has taken place and a problem or question has been identified, it can be useful to break that question up into its component parts using the PICO method.

P     Population      (patient, population, particular conditon under review)

I      Intervention   ( treatment, intervention or exposure)

C    Comparison    (alternative to compare with intervention)

O    Outcome         (affect, improvement or measurement)


P   populations with a high incidence of HIV infection 

I     male circumcision 

C   no circumcision

O   reduced rate of HIV infections amongst heterosexual men

Identify keywords/search terms

Once you have identified your subject terms or keywords and their synonyms, your strategy should look something like this:

  (HIV OR AIDS)  AND (infection OR transmission OR prevention) AND

  (heterosexual males OR heterosexual men)  AND  circumcision

Clinical question and search strategy worksheets

Search strategy templates

These templates will enable you to record your literature searches by indicating  your search strategy, keywords, filters, limits and results.