eTable 4. Level of evidence (LoE) according to the criteria of the Oxford Centre for Evidence-based Medicine (www.cebm.net/index.aspx?o=1025).

Evidence level	Study design
1a	Systematic review of level 1 diagnostic studies;or clinical decision rule with 1b studies from different clinical centres
1b	Validating cohort study with good reference standard; or clinical decision rule tested within one clinical centre
1c	Absolute SpPins und SnNouts*
2a	Systematic review of well-planned cohort studies
2b	A well-planned cohort study or a lesser-quality randomized controlled study
2c	Outcome studies, "ecological studies" = registry studies
3a	Systematic review of 3b and better studies
3b	Nonconsecutive study; or without consistently applied reference standards
4	Case–control study, poor or nonindependent reference standard
5	Expert opinion without explicit critical appraisal of the evidence or based on physiological models/laboratory research

^*"Absolute SpPin", diagnostic finding whose Specificity is so high that a Positive result rules-in the diagnosis; „absolute SnNout“, diagnostic finding whose Sensitivity is so high that a Negative result rules-out the diagnosis