A Systematic Review (SR) is a broad review of existing research on a topic that provides synthesis of the evidence from the collected studies to answer a specific question, to guide development of practice guidelines and inform future research.
SRs are gaining in popularity at medical research institutions across US & AUB and it is estimated that 11 SR are published daily, and take about 18 months to do and several people are involved as thousands of articles have to be assessed. The literature search which is the foundation of SR, takes an average of 6 weeks to develop.
Literature search has to balance between sensitivity & specificity and has to be comprehensive, efficient, up-to-date, and transparent.
So, it is highly recommended to involve a Medical/Health Sciences Librarian as poor search leads to low quality SR; which in turn affects clinical practice adversely; see "engaging medical/health sciences librarians to improve the quality of review articles".
