Everybody agrees that properly conducted systematic reviews can provide a useful evidence base for policy and practice. Systematic reviews with (out) meta-analysis summarize the existing body of information in a more organized way. Though there is consensus on the level and utility of evidence generated by systematic reviews, the logic of ‘being systematic’ in systematic reviews remains to be a debatable issue.
The term systematic means having, showing, or involving a system, method or plan. Thus, a systematic review is a review that has/show/involve a system, method or plan. Different review questions require different methods. Hence, it makes more sense that there are many ways of being systematic. Though some argue against it, most agree that there are multiple ways of ‘being systematic’ in systematic reviews.
There are two common models of being systematic in systematic review. The traditional way of being systematic uses some rigid guidelines in the selection of sources of information, quality assessment, extraction and synthesis of information. Though this model may be good for RCTs, it falls short of addressing other types of studies. The logical way of being systematic is to use explicit, defensible and organized methods to address a review question. In this type, the review question drives the method, not the other way round. Recent research practices favor the logical way of being systematic over the traditional one.