Acute pancreatitis is a sudden inflammation of the pancreas that causes severe abdominal pain. Most cases are mild and get better within a few days with basic supportive treatment such as fluids and pain relief. Currently, all patients with acute pancreatitis are admitted to hospital, even those with a very low risk of complications. This study will test whether patients with mild acute pancreatitis can be safely sent home with close follow-up (telephone calls on days 1, 2, and 3 after discharge and a clinic visit on day 4) instead of staying in hospital. Patients will be randomly assigned to either home management or standard hospitalization. We will compare the rate of treatment failure at 30 days between the two groups. We expect that home management will be as safe as hospitalization, while being more convenient for patients and less costly for the health system.

Acute pancreatitis (AP) is one of the most common gastrointestinal causes of emergency hospital admission worldwide. Approximately 80% of cases are classified as mild according to the revised Atlanta Classification (2012) and resolve without organ failure or local complications within three to five days. Despite this favorable prognosis, current practice mandates universal inpatient admission. Only two small studies have explored outpatient management of mild AP, reporting treatment failure rates of 4-12% in the ambulatory arm; however, neither was prospectively randomized nor adequately powered for non-inferiority.

This trial is a prospective, single-center, open-label, two-arm, parallel-group, randomized controlled non-inferiority trial. Patients presenting with mild AP, confirmed by at least two revised Atlanta (2012) criteria and classified as mild by a SIRS score of 0 and a Harmless Acute Pancreatitis Score (HAPS) of 0, will be randomly allocated in a 1:1 ratio to outpatient management (Group A) or standard inpatient care (Group B). Randomization will use a table of random numbers with a block size of four. Group A patients will receive an initial 4-6 hour supervised observation period in the emergency department, followed by daily teleconsultation on days 1-3 and an in-person clinic visit on day 4. Group B patients will be admitted to hospital per standard institutional protocol. All patients will receive IAP/APA-compliant supportive care and a final 30-day outcome assessment. The primary endpoint is the 30-day treatment failure rate. Non-inferiority will be declared if the upper bound of the one-sided 95% confidence interval for the between-group difference does not exceed 10%.

Inclusion Criteria:

• Age 18 years or older Diagnosis of acute pancreatitis based on at least two of three revised Atlanta (2012) criteria: characteristic abdominal pain; serum lipase or amylase ≥3× upper limit of normal; or characteristic imaging findings Classification as mild acute pancreatitis: SIRS score = 0 and HAPS score = 0 at emergency department presentation Ability to tolerate oral intake at the time of randomisation Provision of written informed consent Presence of a competent caregiver at home Residence within 30-45 minutes' travel time from the hospital Ability to communicate by telephone

Exclusion Criteria:

• Pregnancy or breastfeeding Inability to maintain oral intake for reasons unrelated to acute pancreatitis Acute pancreatitis attributable to tumour, post-ERCP intervention, or abdominal trauma Concurrent choledocholithiasis with or without cholangitis Chronic pancreatitis or history of recurrent acute pancreatitis (≥2 prior episodes) ASA physical status classification ≥ 3 Clinical or radiological features suggesting moderately severe or severe acute pancreatitis Alcohol withdrawal syndrome No competent caregiver at home Residence more than 30-45 minutes from the hospital Inability to communicate by telephone or equivalent means