General Selection and Exclusion Criteria

Study type	-original studies -systematic reviews of sufficient quality:  - research question of systematic review corresponds (largely) to the basic question  - search is performed in at least 2 relevant databases, e.g. Cochrane Library, Medline/PubMed  - reporting of the complete search strategy  - no relevant keywords/search terms are missing
Follow-up period	-minimum follow-up period of 12 months for therapeutic or prognostic studies.
Exclusion criteria	-Case-reports -Expert opinion -Letters -Editorials -Case control studies for diagnostic tests -Narrative reviews