Figure 2.

Scatterplot of predicted probability of postoperative 30-day death (y-axis, depicted with exponential scale) against total score per patient (x-axis). Horizontal dotted lines indicate the levels of death probability corresponding to the average observed mortality (9.1%), half of it (4.55%), and 3-fold higher mortality (27.3%). The four prognostic classes (thresholds indicated by vertical dotted lines) were identified by (1) the scores corresponding to a predicted mortality not exceeding 4.55% (0 or 5 points); (2) the score range including cases with a predicted mortality above 4.55%, but none beyond 9.1% (7–13 points); (3) the score range whereby predicted mortalities exceeded 9.1%; however, with no case over 27.3% (14–19 points); (4) the scores associated with predicted mortality range exceeding 27.3% (score ≥20).