| Age >80 yrs |
| History of cancer |
| History of heart failure or chronic lung disease |
| Heart rate ≥110 beats·min−1 |
| Systolic blood pressure <100 mmHg |
| O2 saturation <90% |
Patients receive a point for each item present. Patients with 0 points are low risk and patients with ≥1 points are high risk. Reproduced and modified from [6] with permission from the publisher.