Aggressive Versus Non-aggressive Goal-directed Fluid Resuscitation in Acute Pancreatitis

WATERFALL is an investigator-initiated international multicenter open-label randomized clinical trial comparing aggressive versus moderate fluid resuscitation in acute pancreatitis. The main outcome variable will be the proportion of patients with moderate-to-severe AP. Aggressive fluid resuscitation will consist in Lactated Ringer Solution (LR) 20 ml/kg bolus (administered over 2 hours) followed by LR 3 ml/kg/h and moderate a LR bolus 10 ml/kg in case of hypovolemia or no bolus in patients with normal volemia, followed by LR 1.5 ml/kg/h. The patients will be assessed at 3 (±1), 12 (±4), 24 (±4), 48 (±4) and 72 (±4) hours from recruitment, and fluid resuscitation will be adjusted to the patient´s clinical and analytical status according to a protocol. Subgroup analysis will include patients with systemic inflammatory response syndrome (SIRS) at admission, with persistent (\>48h) SIRS and with hypovolemia at admission. Based on available data (Sternby et al, Ann Surg 2019) we expect a 35% incidence of moderate to severe AP in the moderate arm. Sample sizes of 372 per arm of treatment (744 patients) achieve 80% power to detect a difference of 10% between the treatment arms at a significance level (alpha) of 0.05 using a two-sided z-testNA, assuming a 10% dropout. These results assume that 3 sequential tests are made using the O'Brien-Fleming spending function to determine the test boundaries. All analyses will be performed on an intention-to-treat basis. The trial could be stop early for efficacy (primary end-point) if the observed two-sided P value is \<0.0002 at the first interim analysis (after 1/3 of patients have been enrolled) or is \<0.012 at second interim analysis (after 2/3 of patients have been enrolled), favoring aggressive fluid resuscitation. At final analysis, the hypothesis that the incidence of moderate-to-severe pancreatitis is similar in the two treatment arms will be rejected if p\<0.046