What is a systematic review?
"A scientific investigation that focuses on a specific question and that uses explicit, planned scientific methods to identify, select, assess, and summarize the findings of similar but separate studies. It may or may not include a quantitative synthesis of the results from separate studies (meta-analysis) depending on the available data." IOM p 1.
Planning and conducting a systematic review is a time intensive research project. Time to completion will vary depending on the scope of the review and the size and availability of the review team. A well-designed systematic review may take a year or more to complete.
The Cochrane Handbook for Systematic Reviews of Interventions provides the following table showing estimated time for each task.
Report at a Glance: Standards for Systematic Reviews. (brief list)