Sarcopenia estimation using psoas major enhances P-POSSUM mortality prediction in older patients undergoing emergency laparotomy: cross-sectional study.

Abstract

Emergency laparotomy is a considerable component of a colorectal surgeon's workload and conveys substantial morbidity and mortality, particularly in older patients. Frailty is associated with poorer surgical outcomes. Frailty and sarcopenia assessment using Computed Tomography (CT) calculation of psoas major area predicts outcomes in elective and emergency surgery. Current risk predictors do not incorporate frailty metrics. We investigated whether sarcopenia measurement enhanced mortality prediction in over-65s who underwent emergency laparotomy and emergency colorectal resection. An analysis of data collected prospectively during the National Emergency Laparotomy Audit (NELA) was conducted. Psoas major (PM) cross-sectional area was measured at the L3 level and a ratio of PM to L3 vertebral body area (PML3) was calculated. Outcome measures included inpatient, 30-day and 90-day mortality. Statistical analysis was conducted using Mann-Whitney, Chi-squared and receiver operating characteristics (ROC). Logistic regression was conducted using P-POSSUM variables with and without the addition of PML3. Nine-hundred and forty-four over-65s underwent emergency laparotomy from three United Kingdom hospitals were included. Median age was 76years (IQR 70-82years). Inpatient mortality was 21.9%, 30-day mortality was 16.3% and 90-day mortality was 20.7%. PML3 less than 0.39 for males and 0.31 for females indicated significantly worse outcomes (inpatient mortality 68% vs 5.6%, 30-day mortality 50.6% vs 4.0%,90-day mortality 64% vs 5.2%, p < 0.0001). PML3 was independently associated with mortality in multivariate analysis (p < 0.0001). Addition of PML3 to P-POSSUM variables improved area under the curve (AUC) on ROC analysis for inpatient mortality (P-POSSUM:0.78 vs P-POSSUM + PML3:0.917), 30-day mortality(P-POSSUM:0.802 vs P-POSSUM + PML3: 0.91) and 90-day mortality (P-POSSUM:0.79 vs P-POSSUM + PML3: 0.91). PML3 is an accurate predictor of mortality in over-65s undergoing emergency laparotomy. Addition of PML3 to POSSUM appears to improve mortality risk prediction.