| Adjustment variables (always in model) | Candidate features | Position of entry into model | Rationale for position |
|---|---|---|---|
| Age, yr (45-64, 65-74, ≥ 75) Preoperative hemoglobin level, g/L (< 100, 100-119, 120-139, ≥ 140) Requires assistance with activities of daily living History of chronic obstructive pulmonary disease History of recent high-risk coronary artery disease History of stroke History of peripheral vascular disease Active cancer Major general surgery Major neurosurgery Urgent/emergency surgery Postoperative sepsis before bleeding MINS before bleeding Postoperative pulmonary embolus before bleeding Postoperative stroke before bleeding | Reoperation for reasons of bleeding | First | Decision for reoperation is somewhat subjective but easy to ascertain |
| No. of units of erythrocytes transfused ≥ 1 v. 0 ≥ 2 v. < 2 ≥ 3 v. < 3 | Second | Decision regarding if and how much to transfuse is subjective, but information is reliably ascertained | |
| Hemoglobin level nadir, g/L < 80 v. ≥ 80 < 70 v. ≥ 70 < 60 v. ≥ 60 | Third | Nadir is dependent on transfusions and time of measurement | |
| Absolute decrease in hemoglobin level from preoperative value (preoperative level - nadir level), g/L ≥ 40 v. < 40 ≥ 50 v. < 50 ≥ 60 v. < 60 | Fourth | Preoperative hemoglobin level may not be available, nadir is dependent on transfusions and time of measurement, and decrease requires (simple) calculation | |
| Decrease in hemoglobin level relative to preoperative value (preoperative level - nadir level)/preoperative level*100%), % ≥ 30 v. < 30 ≥ 40 v. < 40 | Fifth | Preoperative hemoglobin level may not be available, nadir is dependent on transfusions and time of measurement, and a relative decrease represents a less practical calculation for clinicians | |
| Thought to be cause of death | Not entered into model but will automatically become part of diagnostic criteria after other candidate features have been tested | Judgment is subjective but has face validity and is very specific for death |
Note: MINS = myocardial injury after noncardiac surgery.