TABLE 3.

Example of the PICO method of formulating a systematic review question¹²

Population	Intervention	Comparator	Outcome
General population (primary prevention)	Fish	Isocaloric fat placebo	All cause mortality
History of myocardial infarction (secondary prevention)	Fish oil (EPA, DHA) supplement	No placebo	Cardiac death

¹Entries in the table are shown for illustrative purpose and are not meant to be exhaustive.

²Shown in the table are possible choices (not exhaustively populated in this illustrative example) under each of the PICO elements. A question could be formulated by combining items selected under each of the PICO categories. For example, by selecting “general population,” “fish oil supplements,” “isocaloric fat placebo,” and all cause mortality" and adding appropriate modifiers, one would produce the question; “What is the 5-y overall mortality in general populations taking 1 g of fish oil supplement daily compared with those taking a isocaloric fat placebo?”