Psoas Muscle Index and Density as Prognostic Predictors in Patients Hospitalized with Acute Pancreatitis

<b>Background</b>: Early prognostication of acute pancreatitis (AP) patients for those at high risk of complications during hospitalization can facilitate clinical decision-making. Sarcopenia has been proven to be a risk factor for poor prognosis in patients with AP. We aimed to evaluate the association between the muscle parameters measured in computed tomography (CT) and the clinical outcomes of hospitalized patients with AP. <b>Methods</b>: A total of 132 consecutive patients hospitalized between 1 January 2015 and 31 December 2021 for AP with a valid CT scan were analyzed. The first CT conducted during hospitalization was analyzed for psoas muscle area (PMA), index (PMI), and density (PMD) at the L3 vertebral level. The main adverse outcomes indicating a worse prognosis were the development of extrapancreatic complications, infections, ICU transfer, in-hospital mortality, and hospitalization length. <b>Results</b>: The lowest tertile of PMI, as a surrogate for sarcopenia, was significantly correlated with increased rates of extrapancreatic complications, infections, and longer hospitalizations. It was additionally correlated with a worse CT severity index. The results for PMA and PMD also showed worse outcomes, largely mirroring the results for PMI. Although in-hospital mortality was relatively low, none of the patients died in the highest tertile of PMI. A clear cutoff with sufficient predictive capability could not be found. <b>Conclusions</b>: A low psoas muscle index can serve as an additional potential predictive marker for more severe disease and worse outcomes in hospitalized acute pancreatitis patients. More studies are needed to determine its combination with existing prediction tools.