Published papers

OBJECTIVES: In patients with severe acute pancreatitis (SAP), early enteral nutrition (EN) is recommended by major clinical practice guidelines, but the exact timing for the initiation of EN is unknown. METHODS: We conducted a post hoc analysis of the database for a multicenter (44 institutions) retrospective study of patients with SAP in Japan. The patients were classified into 3 groups according to the timing of EN initiation after the diagnosis of SAP: within 24 hours, between 24 and 48 hours, and more than 48 hours. The primary outcome was in-hospital mortality. RESULTS: Of the 1094 study patients, 176, 120, and 798 patients started EN within 24 hours, between 24 and 48 hours, and more than 48 hours after SAP diagnosis, respectively. On multivariable analysis, hospital mortality was significantly better with EN within 48 hours than with more than 48 hours (adjusted odds ratio, 0.49; 95% confidence interval, 0.29-0.83; P < 0.001) but did not significantly differ between the groups with EN starting within 24 hours and between 24 and 48 hours (P = 0.29). CONCLUSIONS: Enteral nutrition within 24 hours may not confer any additional benefit on clinical outcomes compared with EN between 24 and 48 hours.

Objectives: Endoscopic papillectomy (EP) is a low-invasive treatment for duodenal tumors including papilla. The limit of lesion size and local recurrence have been issues in EP. We developed endoscopic submucosal dissection (ESD) for the duodenal tumors including papilla (ESDIP: ESD including papilla) to overcome the problems. The aim of this study was to evaluate the feasibility of ESDIP. Methods: We included the patients who underwent ESDIP from August 2010 to January 2024 in this study. We evaluated the retrospective characteristics of patients and lesions, clinical results of ESDIP and of endoscopic retrograde cholangiopancreatography (ERCP) as prevention for delayed adverse events, and pathological findings. We also calculated the cumulative recurrence rate and overall survival rate at 12 months after ESDIP. Results: Fifty-four patients were included in this study. The mean lesion size was 39 mm. The third-quarter cases revealed a less than half-circumferential lesion, and the one case with a full-circumferential lesion. Resection was accomplished in 96% (n = 52), and also the en-bloc resection rate was 96%. Of the cases in accomplished resection, 98% of patients were intubated with a pancreaticobiliary drainage tube by ERCP. Intraprocedural perforation occurred in eight cases. Delayed bleeding occurred in 10 cases. Delayed perforation was seen only in one case. The incidence of post-ERCP pancreatitis was 25%. Cumulative local recurrence rate and the overall survival rate were 15% and 96%, respectively. Conclusion: ESDIP may be feasible for duodenal tumors including papilla, and is a potential alternative option to avoid pancreaticoduodenectomy.

Background: Microangiopathic hemolytic anemia (MAHA) is a rare paraneoplastic syndrome that has been reported in patients with gastric signet ring cell carcinoma (SRCC). Clinical and prognostic features of MAHA in this setting have been poorly described. Materials and Methods: We conducted a systematic review in 8 databases of gastric SRCC complicated by MAHA and performed a case-control study assessing factors associated with survival in patients with gastric SRCC and MAHA in our pooled cohort compared with age-, sex-, and stage-matched cases of gastric SRCC from the Surveillance, Epidemiology, and End Results (SEER) database. Descriptive analyses were performed and multivariable Cox-proportional hazards regression modeling was used to determine factors associated with overall survival. Results: All identified patients (n = 47) were symptomatic at index presentation, commonly with back/bone pain, and dyspnea. Microangiopathic hemolytic anemia was the first manifestation of gastric SRCC in 94% of patients. Laboratory studies were notable for anemia (median 7.7 g/dL), thrombocytopenia (median 45.5 × 103/μL), and hyperbilirubinemia (median 2.3 mg/dL). All patients with MAHA had metastatic disease at presentation, most often to the bone, bone marrow, and lymph nodes. Median survival in patients with gastric SRCC and MAHA was significantly shorter than a matched SEER-derived cohort with metastatic gastric SRCC (7 weeks vs 28 weeks, P <. 01). In multivariate analysis, patients with MAHA were at significantly increased risk of mortality (HR 3.28, 95% CI 2.11-5.12). Conclusion: Microangiopathic hemolytic anemia is a rare, late-stage complication of metastatic gastric SRCC and is associated with significantly decreased survival compared with metastatic gastric SRCC alone.

Background: Current guidelines recommend treating choledocholithiasis, regardless of symptoms or stone size, with endoscopic retrograde cholangiopancreatography (ERCP). However, asymptomatic choledocholithiasis, discovered incidentally on imaging, may carry a higher risk of ERCP-related adverse events, and some asymptomatic and diminutive stones may not cause biliary adverse events during extended follow-up. Therefore, we aimed to clarify the best treatment strategies for asymptomatic choledocholithiasis based on stone size. Methods: We retrospectively identified patients with incidental imaging-found asymptomatic diminutive (≤ 4 mm) or non-diminutive (> 4 mm) choledocholithiasis and divided them into two groups: those who did not undergo ERCP and were treated when complications arose (on-demand group) and those who underwent ERCP before being symptomatic (intervention group). Adverse events were defined as any biliary or pancreatic complication related to ERCP or arising during observation or after intervention. The primary outcome was the adjusted overall adverse event-free survival using the propensity score-based matching weights method comparing the two groups of stone size. Results: Among 148 patients identified (median follow-up period, 969 days), 68 had diminutive stones and 80 had non-diminutive stones. Of the 68 patients with diminutive stones, 51 were in the on-demand group and 17 in the intervention group. The overall adjusted adverse event-free survival was significantly higher in the on-demand group for diminutive stones (97.4% and 70.1%, respectively, at 3 years; p = 0.01). Discussion: Patients with incidental imaging-detected asymptomatic diminutive choledocholithiasis may benefit from clinical observation, pursuing ERCP when symptoms develop.

Background: Fluid resuscitation is fundamental in acute pancreatitis (AP) treatment. However, the optimal choice between normal saline (NS) and Ringer's solution (RS), and its impact on mortality in critically ill patients, remains controversial. This retrospective cohort study, utilizing a national Japanese inpatient database, investigates this question. Methods: Using the Japanese Diagnosis Procedure Combination database between July 2010 and March 2021, we identified adult patients hospitalized in intensive care units (ICU) or high-dependency care units (HDU) for AP who survived at least three days and received sufficient fluid resuscitation (≥ [10 ml/kg/hr*1 h + 1 ml/kg/hr*71 h] ml) within three days of admission including emergency room infusions. Patients were classified into groups based on the predominant fluid type received: the NS group (> 80% normal saline) and the RS group (> 80% Ringer's solution). Propensity score matching was employed to reduce potential confounding factors and facilitate a balanced comparison of in-hospital mortality between the two groups. Results: Our analysis included 8710 patients with AP. Of these, 657 (7.5%) received predominantly NS, and 8053 (92.5%) received predominantly RS. Propensity score matching yielded 578 well-balanced pairs for comparison. The NS group demonstrated significantly higher in-hospital mortality than the RS group (12.8% [474/578] vs. 8.5% [49/578]; risk difference, 4.3%; 95% confidence interval, 0.3% to 8.3%). Conclusions: In patients admitted to ICU or HDU with AP receiving adequate fluid resuscitation, RS can be a preferred infusion treatment compared to NS.

Importance: Increased cancer risk in first-degree relatives of probands with pancreatic ductal adenocarcinoma (PDAC probands) who carry pathogenic or likely pathogenic germline variants (PGVs) in cancer syndrome-associated genes encourages cascade genetic testing. To date, unbiased risk estimates for the development of cancers on a gene-specific basis have not been assessed. Objective: To quantify the risk of development of PDAC and extra-PDAC among first-degree relatives of PDAC probands who carry a PGV in 1 of 9 cancer syndrome-associated genes-ATM, BRCA1, BRCA2, PALB2, MLH1, MSH2, MSH6, PMS2, and CDKN2A. Design, Setting, and Participants: This case series focused on first-degree relatives of PDAC probands carrying PGVs in specific cancer syndrome-associated genes. The cohort comprised clinic-ascertained patients enrolled in the Mayo Clinic Biospecimen Resource for Pancreas Research registry with germline genetic testing. In total, 234 PDAC probands carrying PGVs were drawn from the prospective research registry of 4562 participants who had undergone genetic testing of cancer syndrome-associated genes. Demographic and cancer-related family histories were obtained by questionnaire. The data were collected from October 1, 2000, to December 31, 2021. Main Outcomes and Measures: For the PDAC probands, the genetic test results of the presence of PGVs in 9 cancer syndrome-associated genes were obtained by clinical testing. Cancers (ovary, breast, uterus or endometrial, colon, malignant melanoma, and pancreas) among first-degree relatives were reported by the probands. Standardized incidence ratios (SIRs) were used to estimate cancer risks among first-degree relatives of PDAC probands carrying a PGV. Results: In total, 1670 first-degree relatives (mean [SD] age, 58.1 [17.8] years; 853 male [51.1%]) of 234 PDAC probands (mean [SD] age, 62.5 [10.1] years; 124 male [53.0%]; 219 [94.4%] White; 225 [98.7%] non-Hispanic or non-Latino]) were included in the study. There was a significantly increased risk of ovarian cancer in female first-degree relatives of probands who had variants in BRCA1 (SIR, 9.49; 95% CI, 3.06-22.14) and BRCA2 (SIR, 3.72; 95% CI, 1.36-8.11). Breast cancer risks were higher with BRCA2 variants (SIR, 2.62; 95% CI, 1.89-3.54). The risks of uterine or endometrial cancer (SIR, 6.53; 95% CI, 2.81-12.86) and colon cancer (SIR, 5.83; 95% CI, 3.70-8.75) were increased in first-degree relatives of probands who carried Lynch syndrome mismatch repair variants. Risk of PDAC was also increased for variants in ATM (SIR, 4.53; 95% CI, 2.69-7.16), BRCA2 (SIR, 3.45; 95% CI, 1.72-6.17), CDKN2A (SIR, 7.38; 95% CI, 3.18-14.54), and PALB2 (SIR, 5.39; 95% CI, 1.45-13.79). Melanoma risk was elevated for first-degree relatives of probands with CDKN2A variants (SIR, 7.47; 95% CI, 3.97-12.77). Conclusions and Relevance: In this case series, the presence of PGVs in 9 cancer syndrome-associated genes in PDAC probands was found to be associated with increased risk of 6 types of cancers in first-degree relatives. These gene-specific PDAC and extra-PDAC cancer risks may provide justification for clinicians to counsel first-degree relatives about the relevance and importance of genetic cascade testing, with the goal of higher uptake of testing.

Metastatic pancreatic cancer is a rare condition and cases of pancreatic metastasis from cervical cancer are infrequently reported. Furthermore, the incidence rates of pancreatic tumors as the cause of pancreatitis and of pancreatitis in patients with pancreatic tumors are similarly low. Pancreatitis may occur when a tumor obstructs the pancreatic duct. This condition may be difficult to manage and significantly reduces the quality of life because of severe abdominal pain. Here, we present a rare case of obstructive pancreatitis caused by pancreatic metastasis from cervical squamous-cell carcinoma, pathologically confirmed using endoscopic ultrasonography-guided fine-needle biopsy and treated with palliative irradiation to achieve rapid therapeutic relief. It is important to obtain appropriate tissue samples, confirm the pathological diagnosis, and compare the pathological findings with those of the primary tumor to select the appropriate treatment for obstructive pancreatitis caused by a metastatic pancreatic tumor.

Background Guidelines recommend that all patients with upper gastrointestinal bleeding (UGIB) undergo endoscopy within 24 h. It is unclear whether a subgroup may benefit from an urgent intervention. We aimed to evaluate the influence of endoscopic hemostasis and urgent endoscopy on mortality in UGIB patients with high-risk stigmata (HRS). Methods Consecutive patients with suspected UGIB were enrolled in three Japanese hospitals with a policy to perform endoscopy within 24 h. The primary outcome was 30-day mortality. Endoscopic hemostasis and endoscopy timing (urgent, ≤6 h; early, >6 h) were evaluated in a regression model adjusting for age, systolic pressure, heart rate, hemoglobin, creatinine, and variceal bleeding in multivariate analysis. A propensity score of 1:1 matched sensitivity analysis was also performed. Results HRS were present in 886 of 1966 patients, and 35 of 886 (3.95%) patients perished. Median urgent-endoscopy time (n = 769) was 3.0 h (interquartile range [IQR], 2.0–4.0 h) and early endoscopy (n = 117) was 12.0 h (IQR, 8.5–19.0 h). Successful endoscopic hemostasis and urgent endoscopy were significantly associated with reduced mortality in multivariable analysis (odds ratio [OR], 0.22; 95% confidence interval [CI], 0.09–0.52; P = 0.0006, and OR, 0.37; 95% CI, 0.16–0.87; P = 0.023, respectively). In a propensity-score-matched analysis of 115 pairs, adjusted comparisons showed significantly lower mortality of urgent vs early endoscopy (2.61% vs 7.83%, P < 0.001). Conclusions A subgroup of UGIB patients, namely those harboring HRS, may benefit from endoscopic hemostasis and urgent endoscopy rather than early endoscopy in reducing mortality. Implementing triage scores that predict the presence of such lesions is important.

The endoscopic diagnosis of biliary tract lesions is applied as a non-invasive method; however, its diagnostic accuracy is not yet high. Moreover, digital cholangioscopy is used for directly visualizing the inside of the bile duct, resulting in a more precise biopsy. We present the case series of the outcomes of diagnosis using digital cholangioscopy in patients who underwent cholangioscopy for the evaluation of biliary stenosis in our department between January 2014 and March 2021. The controls were those who underwent a biopsy for biliary stenosis with conventional endoscopic retrograde cholangiopancreatography (ERCP). Background data for each case were collected, and the clinical outcomes by biopsy were evaluated, focusing on the accuracy of the diagnosis. Cholangioscopy was performed in 15 cases, while a conventional biopsy by ERCP was performed in 172 cases. Nine of 15 cases (60.0%) were diagnosed with cholangiocarcinoma. The number of specimens obtained through conventional ERCP and cholangioscopy was 2.5 ± 1.3 and 3.3 ± 1.5, respectively (p = 0.043). The diagnostic accuracy of conventional ERCP and cholangioscopy were 65.7% (113 of 172 cases) and 100%, respectively, which was significantly higher in the group with cholangioscopy. Digital cholangioscopy is useful when the diagnosis of the biliary stricture using the conventional ERCP method is difficult.

Background & aims: The association between body composition parameters measured on computed tomography (CT) and severity of acute pancreatitis (AP) is conflicting because these composition parameters vary considerably by sex and age. We previously developed normative body composition data, in healthy subjects. Z-score calculated from the normative data gives age and sex adjusted body composition parameters. We studied the above association using this novel Z-score in a large cohort of patients with AP. Methods: Between January 2014 and March 2018, patients admitted with AP and had CT scans within a week of admission, were enrolled. Body composition data including skeletal muscle (SM), subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) were calculated from the CT scan using deep learning automated algorithm. Then we converted the value to Z-score, and then compared the same score between mild AP, moderately severe AP and severe AP defined by revised Atlanta criteria. Results: Out of 514 patients, 336 (65.4%) are mild AP, 130 (25.3%) moderately severe AP, and 48 (9.3%) severe AP. Patients with moderately severe AP had significantly lower SM-z-score than those with mild AP (1.21 vs1.73, p = 0.048) and patients with severe AP had significantly lower SAT-z-score than those with mild AP (0.70 vs.1.29, p = 0.016). VAT-z-score was not significantly different between three groups. (p = 0.76). Conclusion: Lower SM-z-score and SAT-z-score were associated with moderately severe and severe types of AP, respectively. Future prospective studies in patients with AP using Z-scores, may define the association between body composition and severity of AP, and explain the inconsistencies reported in previous studies.

Objectives: Although rectal nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the incidence of postendoscopic retrograde cholangiopancreatography pancreatitis (PEP), their optimal dosage is unknown. Given possible interindividual variability in the pharmacodynamics of NSAIDs, we hypothesized that the dose required to achieve adequate PEP prophylaxis varies with body weight. Materials and Methods: We conducted an analysis using single-center, prospective, observational cohort study data. The primary outcome was PEP incidence by NSAID dosage per body weight (mg/kg). Patients meeting the inclusion criteria were classified into 3 groups. Results: We included 891 patients, with 400, 454, and 37 patients in the control group with no NSAID therapy, the NSAID <1.0 mg/kg group, and the NSAID ≥1.0 mg/kg group, respectively. In the adjusted cohort, the odds ratio of PEP was 0.18 (95% confidence interval: 0.041–0.79; P = 0.023) for NSAID ≥1.0 mg/kg and 1.3 (95% confidence interval: 0.76–2.3; P = 0.31) for NSAID <1.0 mg/kg compared to the control group without NSAID. Conclusions: PEP was not prevented by NSAID dosages below 1.0 mg/ kg body weight whereas a dosage above 1.0 mg/kg body weight had a significant prophylactic effect. An NSAID dosage adjusted to body weight may be necessary to achieve an adequate prophylactic effect against PEP.

Background/Purpose: Insufficient studies exist on capnography efficacy during endoscopic ultrasound or endoscopic retrograde cholangiopancreatography, and no definitive conclusions have been drawn. To evaluate the feasibility and efficacy of a novel mainstream capnography using an over-the-biteblock end-tidal CO2 (EtCO2) detector in decreasing the risk of hypoxemia during endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP). Methods: Patients undergoing EUS or ERCP with conscious sedation at a single Japanese center were randomized to a control or a novel capnography monitored (intervention) group in a 1:1 ratio. Hypoxemia correction maneuvers were pursued if the oxygen saturation decreased to <92% in the control or intervention group and if a 15-s suspension of EtCO2 wave occurred in the intervention group. The primary outcome was the incidence of hypoxemic events, defined as oxygen saturation <90%, during the procedures. Secondary outcomes included technical feasibility of EUS and ERCP with the use of this novel over-the-biteblock monitor. Results: In total, 250 patients were enrolled without dropouts or missing data (control group: 125; capnography group: 125). There was no significant difference in the incidence of hypoxemia between the control and capnography groups (29.6% [37/125] vs. 26.4% [33/125]; p =.573). The estimated odds ratio was 0.925 (95% confidence interval: 0.708–1.208). The EtCO2 concentration was successfully captured without impeding endoscopic maneuvers from the beginning to the end of the procedure in all patients. Conclusions: Although the novel mainstream capnography with an over-the-biteblock EtCO2 detector captures the EtCO2 concentration in EUS or ERCP under conscious sedation, it does not lead to the prevention of hypoxemia.

Biliary strictures caused by inflammation or fibrosis lead to jaundice and cholangitis which often make it difficult to distinguish malignant strictures. In cases when malignancy cannot be excluded, surgery is often performed. The concept of immunoglobulin G4 (IgG4)–related sclerosing cholangitis (SC) as a benign biliary stricture was recently proposed. The high prevalence of the disease in Asian countries has resulted in multiple diagnostic and treatment guidelines; however, there is need to formulate a standardized diagnostic strategy among various countries considering the utility, invasiveness, and cost-effectiveness. We evaluated accuracies of various diagnostic modalities for biliary strictures comparing pathology in the Delphi meetings which were held in Rochester, MN. The diagnostic utility for each modality was graded according to the experts, including gastroenterologists, endoscopists, radiologists, and pathologists from the United States and Japan. Diagnostic utility of 10 modalities, including serum IgG4 level, noninvasive imaging, endoscopic ultrasound, endoscopic retrograde cholangiopancreatography–related diagnostic procedures were advocated and the reasons were specified. Serum IgG4 level, noninvasive imaging, diagnostic endoscopic ultrasound and intraductal ultrasonography under endoscopic retrograde cholangiopancreatography were recognized as useful modalities for the diagnosis. The information in this article will aid in the diagnosis of biliary strictures particularly for distinguishing IgG4–SC from cholangiocarcinoma and/or primary SC.

Pancreatic neuroendocrine neoplasm (panNEN) is a rare malignancy and the second most common type of pancreatic cancer after pancreatic ductal adenocarcinoma (PDAC), but its etiology is poorly understood. We investigated whether the risk factors of panNEN are concordant with those known for PDAC. We performed the largest case-control study to date on panNENs, comprising 927 sporadic nonfunctional panNEN cases and 1807 frequency-matched controls, using data from the Mayo Clinic Biospecimen Resource for Pancreas Research. We assessed associations for obesity, first-degree family history of pancreatic cancer, cigarette smoking, overall type II diabetes mellitus (T2DM), new-onset T2DM (<1 year before panNEN diagnosis), longstanding T2DM (≥5 years), alcohol intake and aspirin use. Multivariable logistic regression was used to calculate odds ratios and 95% confidence intervals (CIs). Our results show that overall T2DM (OR = 1.71, 95% CI: 1.37–2.14) and new-onset T2DM (OR = 2.65, 95% CI: 1.92–3.69) are associated with higher odds of panNEN, but not longstanding T2DM (OR = 1.29, 95% CI: 0.94–1.75). A non-significant elevated odds of panNEN was observed among participants with a positive family history of pancreatic cancer (OR = 1.44, 95% CI: 0.96–2.14). Alcohol use was inversely related to panNEN (OR = 0.52, 95% CI: 0.42–0.66, ever-vs-never). No association was observed for smoking, obesity or aspirin use. These findings indicate that overall T2DM and new-onset T2DM are associated with higher odds of panNEN. Unlike PDAC, alcohol use was inversely related to panNEN, and we found no associations for cigarette smoking, obesity or aspirin use. These results indicate differences in the risk factor profiles of panNEN and PDAC.

Objectives: We aim to assess the early use of contrast-enhanced computed tomography (CECT) of patients with severe acute pancreatitis (SAP) using the computed tomography severity index (CTSI) in prognosis prediction. The CTSI combines quantification of pancreatic and extrapancreatic inflammation with the extent of pancreatic necrosis. Methods: Post-hoc retrospective analysis of a large, multicentric database (44 institutions) of SAP patients in Japan. The area under the curve (AUC) of the CTSI for predicting mortality and the odds ratio (OR) of the extent of pancreatic inflammation and necrosis were calculated using multivariable analysis. Results: In total, 1097 patients were included. The AUC of the CTSI for mortality was 0.65 (95 % confidence interval [CI:] [0.59–0.70]; p < 0.001). In multivariable analysis, necrosis 30–50 % and >50 % in low-enhanced pancreatic parenchyma (LEPP) was independently associated with a significant increase in mortality, with OR 2.04 and 95 % CI 1.01–4.12 (P < 0.05) and OR 3.88 and 95 % CI 2.04–7.40 (P < 0.001), respectively. However, the extent of pancreatic inflammation was not associated with mortality, regardless of severity. Conclusions: The degree of necrosis in LEPP assessed using early CECT of SAP was a better predictor of mortality than the extent of pancreatic inflammation.

Objectives: This study evaluated a novel contrast-enhanced (CE) fluoroscopy protocol for endoscopic retrograde cholangiopancreatography, which optimizes image processing to enhance contrast of devices and contrast media. We compared the CE protocol with the conventional standard protocol to assess its potential for reducing radiation exposure while improving image visibility. Methods: The study utilized a multidirectional fluoroscopy unit and phantoms to evaluate the new CE protocol against the conventional protocol. Comparisons included radiation dose rates, spatial resolution, and concentration resolution under various fluoroscopic conditions. The investigation aimed to determine if the CE protocol offered improved visibility while potentially reducing radiation exposure. Results: Three CE protocol modes (LOW-7.5 fps, MID-3.75 fps, and LOW-3.75 fps) achieved lower dose rates than the standard MID-7.5 fps mode commonly used in clinical practice. Dynamic spatial resolution was significantly superior in all three CE modes compared to the standard protocol (p < 0.0167). Static spatial resolution did not differ significantly between protocols. Only the CE MID-3.75 fps mode showed superior concentration resolution compared to the standard protocol (p < 0.00833). Conclusions: The novel CE fluoroscopy protocol provides superior dynamic spatial resolution in endoscopic retrograde cholangiopancreatopgraphy while reducing radiation exposure, potentially enhancing procedure guidance and safety for both patients and clinicians.

Objectives: Early enteral nutrition is recommended for patients with severe acute pancreatitis (AP); however, nutritional management strategies for patients with mild AP have not been established. The aim of this study was to evaluate the benefits and safety of immediate oral intake of low-fat solid food in patients with mild AP who were allowed to take opioid analgesics. Methods: In this single-center randomized study, the immediate feeding (IMF) group was permitted immediate oral intake of low-fat (15 g/d) solid food. In the standard food (STF) group, patients received gradually increasing amounts of dietary fat. Twenty-six patients were randomized, with 13 allocated to each group. The primary outcome was the period between diagnosis and recovery from AP. The cost and rate of progression to severe disease were evaluated as secondary outcomes. Results: The IMF group (mean recovery days: 2 ± 1) recovered significantly earlier (mean difference in recovery days: 6.3; 95% confidence interval [CI], 4.8–7.9; P < 0.001) than the STF group (mean recovery days: 8.3 ± 2.3), with a lower overall treatment cost (mean difference in costs: −$460; 95% CI, −$880 to –$40; P = 0.034). The IMF group showed a lower rate of progression to severe AP (IMF, 0%; STF, 15.3%; P = 0.48). Conclusion: The initial treatment strategy for mild AP should be altered from the gradual introduction of oral feeding upon the absence of pain to immediate oral nutrition with opioid analgesics, to improve treatment efficacy and reduce treatment cost.