A systematic review can be defined as a "scientific investigation that focuses on a specific question and uses explicit, prespecified scientific methods to identify, select, assess, and summarize the findings of similar but separate studies."
1) Systematic reviews aim to minimize bias by using explicit and systematic methods. To reach such a goal, systematic reviews seek to collate all evidence that fits pre-specified eligibility criteria in order to address a specific research question. The key characteristics of a systematic review are 1) a clearly stated set of objectives with pre-defined eligibility criteria for studies; 2) explicit, reproducible methodology; 3) a systematic search that attempts to identify all studies that would meet the eligibility criteria; 4) an assessment of the validity of the findings of the included studies, for example through the assessment of risk of bias; and 5) a systematic presentation, and synthesis, of the characteristics and findings of the included studies.
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The number of systematic reviews is growing rapidly. In PubMed, the number of systematic reviews indexed increased from 2,167 in 2005 to 5,573 in 2011. However, the number of systematic reviews indexed in KoreaMed is less than 100, and the number published in the Korean Journal of Family Medicine or the Journal of Korean Academy of Family Medicine is less than 10. So it can be said that systematic review research had been increasing in foreign countries, but not in Korea, nor in family medicine in Korea.
As a research methodology in family medicine field, systematic review has many advantages. First, the citation impact of systematic review is more than other study designs.
3) Second, it is easier to be published in a Science Citation Index journal than other study design. Third, it does not require institutional review board approval for research. However, in order to be a trustworthy and reliable systematic review, the quality of the systematic review process must be improved. Core standards for systematic review may include 1) writing the review protocol, 2) comprehensive literature search, 3) duplicate study selection and data extraction, 4) assessment of scientific quality of the included studies, 5) appropriate meta-analysis methodology, and 6) reporting according to guidelines (preferred reporting items for systematic reviews and meta-analyses
4) checklist).
Well-conducted systematic review will help make clear what is known and not known about the potential benefits and harms of interventions. Thus, systematic reviews are essential for clinicians who strive to integrate research findings into their daily practices. They must, however, meet certain standards in order to be of such use.