Cutoff Value of Psoas Muscle Area as Reduced Muscle Mass and Its Association with Acute Pancreatitis in China.

Objective: The Global Leadership Initiative on Malnutrition (GLIM) has proposed criteria for the diagnosis of malnutrition, one of which is reduced muscle mass. Computed tomography (CT) assessment of psoas muscle area (PMA) has been used to estimate muscle mass in patients, including those with acute pancreatitis (AP). The present study aimed to define the cutoff value of PMA indicative of reduced muscle mass in patients with AP and to assess the impact of reduced muscle mass on the severity and early complications of AP.

Methods: Clinical data of 269 patients with AP were analyzed retrospectively. The severity of AP was determined according to the revised Atlanta classification. PMA was evaluated by CT and used to calculate the psoas muscle index (PMI). Cutoff values for reduced muscle mass were calculated and validated. Logistic regression analysis was performed to assess the relationship between PMA and the severity of AP.

Results: PMA was a better indicator of reduced muscle mass than PMI, with cutoff values of 11.50 cm for men and 8.22 cm for women. Rates of local complications, splenic vein thrombosis, and organ failure were significantly higher in AP patients with low than high PMA (all p < 0.05). PMA showed good ability to predict splenic vein thrombosis in women, with an area under the receiver operating characteristic curve of 0.848 (95% confidence interval 0.768-0.909, sensitivity 100%, specificity 83.64%). Multivariate logistic regression revealed that PMA was an independent risk factor for moderately severe plus severe AP (odds ratio 5.639, p = 0.001) and severe AP (odds ratio 3.995, p = 0.038).

Conclusion: PMA is a good predictor of the severity and complications of AP. The PMA cutoff value is a good indicator of reduced muscle mass.