Comparative effectiveness of elemental formula in the early enteral nutrition management of acute pancreatitis: a retrospective cohort study

BACKGROUND: Although enteral nutrition has become one of the standard therapies for patients with acute pancreatitis, the optimal formulae for enteral nutrition have been under debate. Elemental formula is assumed to be suitable in the treatment of patients with acute pancreatitis because it has less stimulating effects for exocrine secretions of the pancreas, simultaneously maintaining gut immunity; however, clinical studies corroborating this assumption have been scarce. METHODS: We conducted a retrospective cohort study using a Japanese national administrative database between 2010 and 2015. Patients with acute pancreatitis who received enteral feeding within 3 days of admission were identified and divided into two groups according to whether elemental formula was administered. We assessed the impact of elemental formula for the outcomes (primary, in-hospital mortality; secondary, development of sepsis, hospital-free days at 90 days, and total health-care costs) using a multivariate mixed-effect regression analysis and propensity score matching analysis adjusted by a well-validated case-mix adjustment model. Analysis for the subpopulation of patients with severe acute pancreatitis was also performed. RESULTS: Of 243,312 patients with acute pancreatitis, 948 patients were identified and classified into the elemental formula group (N = 382) and the control group (N = 566). No significant differences were observed for in-hospital mortality [10.2% in the elemental formula group vs. 11.0% in the control group; adjusted adds ratio (95% confidence interval; CI) = 0.94 (0.53–1.67)], sepsis development [5.0 vs. 7.1%; adjusted adds ratio (95% CI) = 0.66 (0.34–1.28)], mean hospital-free days [54 days vs. 51 days; adjusted difference (95% CI) = 2 days (− 2 to 5)], and mean total health-care costs [$29,360 vs. $34,214; adjusted difference (95% CI) = − $4250 (− 8643 to 141)]. Similar results were also observed in patients with severe acute pancreatitis. CONCLUSIONS: The results of our retrospective cohort study using a large-scale national database did not demonstrate the benefit of elemental formula compared to semi-elemental and polymeric formulae in patients with acute pancreatitis. Further assessment of alternative nutritional strategy is expected. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13613-018-0414-6) contains supplementary material, which is available to authorized users.