In this example below, the individual components are searched first, utiliizing OR to combine terms 1 and 2. The finalized result set (search #15) is obtained by combining these searches with AND and applying limits. Organization of the search strategy in this manner facilitates evaluation by the systematic review team and provides the reader with a display which is easier to follow in the published article.
The following search example in PubMed utilizing P, I and O components for the research question "In patients with autism, does music therapy improve social interaction." Note that this statement does not include a comparison. Keyword truncation (*) and MeSH terms are both applied to this search. The final search #10 shows that the filters for Clinical Trial and published in the last 5 years resulted in a set of seven citations.
Consider using a preconfigured search strategy--also called a hedge or filter--to help retrieve more relevant citations. These sites include hedges for topics such as randomozied controlled trials, qualitative research, age groups, etc. Some also include information on the quality of the hedges: have they been validated? Are they current?