ToolsCalculators
Obesity Surgery Mortality Risk Score (OS-MRS)
Estimates perioperative mortality risk before bariatric (gastric bypass) surgery.
Obesity Surgery Mortality Risk Score (OS-MRS)
BMI ≥50 kg/m²
Male sex
Hypertension
Known risk factor for pulmonary embolism
Prior venous thromboembolism, IVC filter in place, hypoventilation syndrome/obstructive sleep apnea, or pulmonary hypertension.
Age ≥45 years
Result0 points
Class A risk group; reported perioperative mortality approximately ~0.2 %.
- Risk class
- Class A
- Reported mortality
- ~0.2 %
When to use
- Preoperative risk stratification before Roux-en-Y gastric bypass or other bariatric procedures.
Formula
One point each: BMI ≥50, male sex, hypertension, known PE risk factor, age ≥45. Class A 0–1, Class B 2–3, Class C 4–5.
Pearls and pitfalls
- Derived and validated in gastric bypass cohorts; applicability to other bariatric procedures (e.g. sleeve gastrectomy) is less well studied.