Fig. 1

Population diagram to illustrate clinical ramifications of the Canadian Syncope Risk Score for acute management of syncope (cut-point “low risk”). Each circle in the figure represents one person (1000 in total) presenting in the emergency department with syncope, of whom approximately 36 will sustain a serious adverse event (shaded circle) and 964 will not (unshaded circle). Red cells (460) indicate people deemed “at risk” using the risk score with a cut-point of “low risk”. Green cells are people deemed not “at risk”. These natural frequencies are derived from the reported sensitivity of 93%; specificity 56% (for the low-risk cut-point); and prevalence (0.036) in the internally validated model [30]. The internally validated C-statistic for the developed model was 0.88 (95%CI 0.85, 0.90).