Systematic review

Systematic reviews are generally regarded as the highest level of medical evidence by evidence-based medicine professionals. An understanding of systematic reviews and how to implement them in practice is becoming mandatory for all professionals involved in the delivery of health care.

A systematic review is a summary of the healthcare literature that uses explicit methods to perform a thorough literature search and critical appraisal of individual studies to identify the valid and applicable evidence, and then uses appropriate techniques to combine these valid studies.

Most systematic reviews are based on a quantitative meta-analysis of available data, but there are also some more qualitative reviews which adhere to the standards for gathering, analyzing and reporting evidence.

Many healthcare journals now publish systematic reviews, but the best-known source of them is the Cochrane Collaboration, a group of over 6,000 specialists in health care who systematically review biomedical trials and results of other research. Cochrane reviews are published in the Cochrane Database of Systematic Reviews section of the Cochrane Library, which to date (November 2005) contains 2,524 complete reviews and 1,589 protocols.

The Cochrane Group provides a handbook for systematic reviewers of interventions, where they suggest that each systematic review should contain the following main sections:


 * Background
 * Objectives
 * Methods of the review
 * Results
 * Conclusion and discussion

There are seven steps for preparing and maintaining a systematic review, as outlined in the Cochrane Handbook:


 * 1) Formulating a problem
 * 2) Locating and selecting studies
 * 3) Critical appraisal of studies
 * 4) Collecting data
 * 5) Analyzing and presenting results
 * 6) Interpreting results
 * 7) Improving and updating reviews