[Planning the searches for a systematic review].

The planning of a systematic search is of great importance to the results. The systematic searches are planned as part of a protocol, which is developed to minimise bias. The development of the search strategy uses elements from a conceptualisation model. The information sources are selected based on the review question and should include more than one bibliographic database and possibly grey literature. Search terms are defined, and the thesauri of the databases should be used if possible. Any alternative search strategies may be considered. Finally, the searches must be reported in detail. Those points are discussed in this review.