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Background Periodontal disease, including periodontitis, has been reported to be a rare cause of septic pulmonary embolism (SPE). It is however extremely difficult to isolate the causative pathogen of periodontal disease-associated SPE from blood cultures of these patients. Case presentation In this study, an 85-year-old Japanese man was admitted with fever and worsening malaise. He was later noted to have multiple bilateral subpleural pulmonary nodules on chest computed tomography scan. After admission, Parvimonas micra (P. micra) was isolated from his blood culture. This was followed by a meticulous search for the primary source of SPE, focusing on the head and neck areas. Consequently, apical periodontitis and infratemporal fossa abscess were identified as the primary sources of SPE. Although P. micra is one of the most frequently detected bacteria in the infected root canals of teeth with chronic apical periodontitis, it has rarely been proven as a causative pathogen of periodontal disease-associated SPE. Conclusions This case study demonstrated that periodontal disease is an important primary source of SPE and P. micra could be a causative pathogen of SPE.

BACKGROUND Rapid urinary trypsinogen-2 dipstick test and levels of urinary trypsinogen-2 and trypsinogen activation peptide (TAP) concentration have been reported as prognostic markers for the diagnosis of acute pancreatitis. AIM To reconfirm the validity of all these markers in the diagnosis of acute pancreatitis by undertaking a multi-center study in Japan. METHODS Patients with acute abdominal pain were recruited from 17 medical institutions in Japan from April 2009 to December 2012. Urinary and serum samples were collected twice, at enrollment and on the following day for measuring target markers. The diagnosis and severity assessment of acute pancreatitis were assessed based on prognostic factors and computed tomography (CT) Grade of the Japanese Ministry of Health, Labour, and Welfare criteria. RESULTS A total of 94 patients were enrolled during the study period. The trypsinogen-2 dipstick test was positive in 57 of 78 patients with acute pancreatitis (sensitivity, 73.1%) and in 6 of 16 patients with abdominal pain but without any evidence of acute pancreatitis (specificity, 62.5%). The area under the curve (AUC) score of urinary trypsinogen-2 according to prognostic factors was 0.704, which was highest in all parameter. The AUC scores of urinary trypsinogen-2 and TAP according to CT Grade were 0.701 and 0.692, respectively, which shows higher than other pancreatic enzymes. The levels of urinary trypsinogen-2 and TAP were significantly higher in patients with extended extra-pancreatic inflammation as evaluated by CT Grade. CONCLUSION We reconfirmed urinary trypsinogen-2 dipstick test is useful as a marker for the diagnosis of acute pancreatitis. Urinary trypsinogen-2 and TAP may be considered as useful markers to determine extra-pancreatic inflammation in acute pancreatitis.

Background Correctly identifying anaerobic bloodstream infections (BSIs) is difficult. However, a new technique, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), enables more accurate identification and appropriate treatment. Anaerobic BSIs identified by MALDI-TOF MS were retrospectively analyzed to determine the clinical and microbiological features and patient outcomes based on the anaerobic genera or group. Methods Medical records of patients with anaerobic BSIs were used to conduct a single-center retrospective cohort study from January 2016 to December 2020 in Nagoya, Japan. Multivariate logistic regression analysis was performed to determine the independent risk factors for in-hospital mortality. Results Of the 215 patients with anaerobic BSIs, 31 had multiple anaerobic organisms in the blood culture, including 264 total episodes of anaerobic BSIs. Bacteroides spp. were isolated the most (n = 74), followed by gram-positive non-spore-forming bacilli (n = 57), Clostridium spp. (n = 52), gram-positive anaerobic cocci (GPAC) (n = 27), and gram-negative cocci (n = 7). The median patient age was 76 years; 56.7% were male. The most common focal infection site was intra-abdominal (36.7%). The in-hospital mortality caused by anaerobic BSIs was 21.3%, and was highest with Clostridium spp. (36.5%) and lowest with GPAC (3.7%). Age, solid tumors, and Clostridium spp. were independent risk factors for in-hospital mortality. Conclusions We identified current anaerobic BSI trends using MALDI-TOF MS and reported that mortality in patients with anaerobic BSIs patients was highest with Clostridium spp. infections.

The initial management of patients with suspected acute biliary infection starts with the measurement of vital signs to assess whether or not the situation is urgent. If the case is judged to be urgent, initial medical treatment should be started immediately including respiratory/circulatory management if required, without waiting for a definitive diagnosis. The patient's medical history is then taken; an abdominal examination is performed; blood tests, urinalysis, and diagnostic imaging are carried out; and a diagnosis is made using the diagnostic criteria for cholangitis/cholecystitis. Once the diagnosis has been confirmed, initial medical treatment should be started immediately, severity should be assessed according to the severity grading criteria for acute cholangitis/cholecystitis, and the patient's general status should be evaluated. For mild acute cholangitis, in most cases initial treatment including antibiotics is sufficient, and most patients do not require biliary drainage. However, biliary drainage should be considered if a patient does not respond to initial treatment. For moderate acute cholangitis, early endoscopic or percutaneous transhepatic biliary drainage is indicated. If the underlying etiology requires treatment, this should be provided after the patient's general condition has improved; endoscopic sphincterotomy and subsequent choledocholithotomy may be performed together with biliary drainage. For severe acute cholangitis, appropriate respiratory/circulatory management is required. Biliary drainage should be performed as soon as possible after the patient's general condition has been improved by initial treatment and respiratory/circulatory management. Free full articles and mobile app of TG18 are available at: http://www.jshbps.jp/modules/en/index.php?content_id=47. Related clinical questions and references are also included.

In some cases, laparoscopic cholecystectomy (LC) may be difficult to perform in patients with acute cholecystitis (AC) with severe inflammation and fibrosis. The Tokyo Guidelines 2018 (TG18) expand the indications for LC under difficult conditions for each level of severity of AC. As a result of expanding the indications for LC to treat AC, it is absolutely necessary to avoid any increase in bile duct injury (BDI), particularly vasculo-biliary injury (VBI), which is known to occur at a certain rate in LC. Since the Tokyo Guidelines 2013 (TG13), an attempt has been made to assess intraoperative findings as objective indicators of surgical difficulty; based on expert consensus on these difficulty indicators, bail-out procedures (including conversion to open cholecystectomy) have been indicated for cases in which LC for AC is difficult to perform. A bail-out procedure should be chosen if, when the Calot's triangle is appropriately retracted and used as a landmark, a critical view of safety (CVS) cannot be achieved because of the presence of nondissectable scarring or severe fibrosis. We propose standardized safe steps for LC to treat AC. To achieve a CVS, it is vital to dissect at a location above (on the ventral side of) the imaginary line connecting the base of the left medial section (Segment 4) and the roof of Rouviere's sulcus and to fulfill the three criteria of CVS before dividing any structures. Achieving a CVS prevents the misidentification of the cystic duct and the common bile duct, which are most commonly confused. Free full articles and mobile app of TG18 are available at: http://www.jshbps.jp/modules/en/index.php?content_id=47. Related clinical questions and references are also included.

Since the publication of the Tokyo Guidelines in 2007 and their revision in 2013, appropriate management for acute cholecystitis has been more clearly established. Since the last revision, several manuscripts, especially for alternative endoscopic techniques, have been reported; therefore, additional evaluation and refinement of the 2013 Guidelines is required. We describe a standard drainage method for surgically high-risk patients with acute cholecystitis and the latest developed endoscopic gallbladder drainage techniques described in the updated Tokyo Guidelines 2018 (TG18). Our study confirmed that percutaneous transhepatic gallbladder drainage should be considered the first alternative to surgical intervention in surgically high-risk patients with acute cholecystitis. Also, endoscopic transpapillary gallbladder drainage or endoscopic ultrasound-guided gallbladder drainage can be considered in high-volume institutes by skilled endoscopists. In the endoscopic transpapillary approach, either endoscopic naso-gallbladder drainage or gallbladder stenting can be considered for gallbladder drainage. We also introduce special techniques and the latest outcomes of endoscopic ultrasound-guided gallbladder drainage studies. Free full articles and mobile app of TG18 are available at: http://www.jshbps.jp/modules/en/index.php?content_id=47. Related clinical questions and references are also included.

Antimicrobial therapy is a mainstay of the management for patients with acute cholangitis and/or cholecystitis. The Tokyo Guidelines 2018 (TG18) provides recommendations for the appropriate use of antimicrobials for community-acquired and healthcare-associated infections. The listed agents are for empirical therapy provided before the infecting isolates are identified. Antimicrobial agents are listed by class-definitions and TG18 severity grade I, II, and III subcategorized by clinical settings. In the era of emerging and increasing antimicrobial resistance, monitoring and updating local antibiograms is underscored. Prudent antimicrobial usage and early de-escalation or termination of antimicrobial therapy are now important parts of decision-making. What is new in TG18 is that the duration of antimicrobial therapy for both acute cholangitis and cholecystitis is systematically reviewed. Prophylactic antimicrobial usage for elective endoscopic retrograde cholangiopancreatography is no longer recommended and the section was deleted in TG18. Free full articles and mobile app of TG18 are available at: http://www.jshbps.jp/modules/en/index.php?content_id=47. Related clinical questions and references are also included.

Background The Tokyo Guidelines 2007 (TG07) first presented the diagnostic and severity grading criteria for acute cholangitis. Subsequently updated in 2013, the Tokyo Guidelines (TG13) have been widely adopted throughout the world as global standard guidelines. We set out to verify the efficacy of these TG13 criteria in an international multicenter study. Methods We reviewed 6,063 patients who were clinically diagnosed with acute cholangitis in Japan and Taiwan over a 2-year period. The TG13 diagnostic and severity grading criteria were retrospectively applied, and 30-day mortality was investigated. Results A diagnosis of acute cholangitis was made in 5,454 (90.0%) patients on the basis of the TG13 criteria, and in 4,815 (79.4%) patients on the basis of the TG07 criteria. The 30-day mortality rates of patients with Grade III, Grade II, and Grade I were 5.1%, 2.6%, and 1.2%, respectively, and increased significantly along with disease severity. The mortality rate in the 1,272 Grade II cases where urgent or early biliary drainage was performed was 2.0% (n = 25), which was significantly lower than that of 3.7% (n = 28) in the other 748 cases. Conclusion By using the TG13 diagnostic and severity grading criteria, more patients with possible acute cholangitis can be diagnosed, and patients whose prognosis can potentially be improved by early biliary drainage can be identified. The TG13 criteria are appropriate and useful for clinical practice.

Background The collaborative multicenter retrospective study of acute cholecystitis (AC) was performed in Japan and Taiwan. The aim for this study was evaluation of the clinical value of TG13 severity grading for AC. Method The study was designed as an international multicenter retrospective study of AC from 2011 to 2013. Based on the data, we investigated the TG13 severity grading by analyzing the correlations between grade and prognosis, surgical procedures, histopathology, and organ dysfunction and prognosis. Results An investigation revealed that 30-day overall mortality rate was 1.1% for Grade I, 0.8% for Grade II, 5.4% for Grade III. The mortality rate for Grade III was significantly higher than lower grades (P

Background Since the publication of the Tokyo Guidelines (TG13) for the management of acute cholecystitis (AC), multidirectional studies have been published. However, epidemiological research about AC with big data was not projected. The aim of this study was to reveal the actual clinical conditions of AC. Method The study was designed as an international multicenter retrospective study of AC in Japan and Taiwan from 2011 to 2013. The factors investigated comprised data related to demographic, history, physical examinations, laboratory and imaging findings. Based on these data, we investigated the various values of AC, and real situation with respect to severity and treatment. Results A total of 5,459 patients with AC were reviewed. Thirty-day mortality rate was 1.1%. Based on the diagnostic criteria, 4,088 patients had a definite diagnosis and 291 had a suspected diagnosis. According to the severity grading, 939 patients were classified as Grade III, 2,308 as Grade II, and 2,130 as Grade I. Cholecystectomy was performed in total of 4,266 patients and 2,765 patients had laparoscopic cholecystectomy. The main etiologies were gallbladder stones in 4,623 cases. Conclusion This epidemiological study with large population will undoubtedly contribute to establish the best practice for managing AC worldwide.

We propose a new flowchart for the treatment of acute cholecystitis (AC) in the Tokyo Guidelines 2018 (TG18). Grade III AC was not indicated for straightforward laparoscopic cholecystectomy (Lap-C). Following analysis of subsequent clinical investigations and drawing on Big Data in particular, TG18 proposes that some Grade III AC can be treated by Lap-C when performed at advanced centers with specialized surgeons experienced in this procedure and for patients that satisfy certain strict criteria. For Grade I, TG18 recommends early Lap-C if the patients meet the criteria of Charlson comorbidity index (CCI) ≤5 and American Society of Anesthesiologists physical status classification (ASA-PS) ≤2. For Grade II AC, if patients meet the criteria of CCI ≤5 and ASA-PS ≤2, TG18 recommends early Lap-C performed by experienced surgeons; and if not, after medical treatment and/or gallbladder drainage, Lap-C would be indicated. TG18 proposes that Lap-C is indicated in Grade III patients with strict criteria. These are that the patients have favorable organ system failure, and negative predictive factors, who meet the criteria of CCI ≤3 and ASA-PS ≤2 and who are being treated at an advanced center (where experienced surgeons practice). If the patient is not considered suitable for early surgery, TG18 recommends early/urgent biliary drainage followed by delayed Lap-C once the patient's overall condition has improved. Free full articles and mobile app of TG18 are available at: http://www.jshbps.jp/modules/en/index.php?content_id=47. Related clinical questions and references are also included.

Although the diagnostic and severity grading criteria on the 2013 Tokyo Guidelines (TG13) are used worldwide as the primary standard for management of acute cholangitis (AC), they need to be validated through implementation and assessment in actual clinical practice. Here, we conduct a systematic review of the literature to validate the TG13 diagnostic and severity grading criteria for AC and propose TG18 criteria. While there is little evidence evaluating the TG13 criteria, they were validated through a large-scale case series study in Japan and Taiwan. Analyzing big data from this study confirmed that the diagnostic rate of AC based on the TG13 diagnostic criteria was higher than that based on the TG07 criteria, and that 30-day mortality in patients with a higher severity based on the TG13 severity grading criteria was significantly higher. Furthermore, a comparison of patients treated with early or urgent biliary drainage versus patients not treated this way showed no difference in 30-day mortality among patients with Grade I or Grade III AC, but significantly lower 30-day mortality in patients with Grade II AC who were treated with early or urgent biliary drainage. This suggests that the TG13 severity grading criteria can be used to identify Grade II patients whose prognoses may be improved through biliary drainage. The TG13 severity grading criteria may therefore be useful as an indicator for biliary drainage as well as a predictive factor when assessing the patient's prognosis. The TG13 diagnostic and severity grading criteria for AC can provide results quickly, are minimally invasive for the patients, and are inexpensive. We recommend that the TG13 criteria be adopted in the TG18 guidelines and used as standard practice in the clinical setting. Free full articles and mobile app of TG18 are available at: http://www.jshbps.jp/modules/en/index.php?content_id=47. Related clinical questions and references are also included.

Background Although early laparoscopic cholecystectomy is widely performed for acute cholecystitis, the optimal timing of a cholecystectomy in clinically ill patients remains controversial. This study aims to determine the best practice for the patients presenting with acute cholecystitis focused on disease severity and comorbidities. Methods An international multicentric retrospective observational study was conducted over a 2-year period. Patients were divided into four groups: Group A: primary cholecystectomy; Group B: cholecystectomy after gallbladder drainage; Group C: gallbladder drainage alone; and Group D: medical treatment alone. Results The subjects of analyses were 5,329 patients. There were statistically significant differences in mortality rates between patients with Charlson comorbidity index (CCI) scores below and above 6 (P < 0.001). The shortest operative time was observed in Group A patients who underwent surgery 0–3 days after admission (P < 0.01). Multiple regression analysis revealed CCI and low body mass index

Background The international practice guidelines for patients with acute cholangitis and cholecystitis were released in 2007 (TG 07) and revised in 2013 (TG 13).This study investigated updated epidemiology and outcomes among patients with acute cholangitis on a larger scale for the first time. Methods This is an international multi-center retrospective observational study in Japan and Taiwan. All consecutive patients older than 18 years of age and given a clinical diagnosis of acute cholangitis by clinicians between January 1, 2011 and December 31, 2012 were enrolled. Those who met the diagnostic criteria of acute cholangitis by TG13 were statistically analyzed. Results A total of 7,294 patients were enrolled and 6,433 patients met the TG 13 diagnostic criteria. The severity distribution was Grade I (37.5%), Grade II (36.2%), and Grade III (26.2%). The 30 day all cause-mortality was 2.4%, 4.7%, and 8.4% in Grade I, II, III severity, respectively (p< 0.001). The incidence of liver abscess and endocarditis as complications of acute cholangitis was 2.0% and 0.26%, respectively. Conclusions This is the first large scale study to investigate patients with acute cholangitis. This study provides the basis to define the best practices to manage patients with acute cholangitis in future studies. This article is protected by copyright. All rights reserved.

Since its publication in 2007, the Tokyo Guidelines for the management of acute cholangitis and cholecystitis (TG07) have been widely adopted. The validation of TG07 conducted in terms of clinical practice has shown that the diagnostic criteria for acute cholecystitis are highly reliable but that the definition of definite diagnosis is ambiguous. Discussion by the Tokyo Guidelines Revision Committee concluded that acute cholecystitis should be suspected when Murphy’s sign, local inflammatory findings in the gallbladder such as right upper quadrant abdominal pain and tenderness, and fever and systemic inflammatory reaction findings detected by blood tests are present but that definite diagnosis of acute cholecystitis can be made only on the basis of the imaging of ultrasonography, computed tomography or scintigraphy (HIDA scan). These proposed diagnostic criteria provided better specificity and accuracy rates than the TG07 diagnostic criteria. As for the severity assessment criteria in TG07, there is evidence that TG07 resulted in clarification of the concept of severe acute cholecystitis. Furthermore, there is evidence that severity assessment in TG07 has led to a reduction in the mean duration of hospital stay. As for the factors used to establish a moderate grade of acute cholecystitis, such as leukocytosis, ALP, old age, diabetes, being male, and delay in admission, no new strong evidence has been detected indicating that a change in the criteria used in TG07 is needed. Therefore, it was judged that the severity assessment criteria of TG07 could be applied in the updated Tokyo Guidelines (TG13) with minor changes. TG13 presents new standards for the diagnosis, severity grading and management of acute cholecystitis. Free full-text articles and a mobile application of TG13 are available via http://www.jshbps.jp/en/guideline/tg13.html .

Background The Tokyo Guidelines for the management of acute cholangitis and cholecystitis (TG07) were published in 2007 as the world's first guidelines for acute cholangitis and cholecystitis. The diagnostic criteria and severity assessment of acute cholecystitis have since been widely used all over the world. A validation study of TG07 has shown that the diagnostic criteria for acute cholecystitis are highly reliable but that the definition of definite diagnosis is ambiguous. In addition, considerable new evidence referring to acute cholecystitis as well as evaluations of TG07 have been published. Consequently, we organized the Tokyo Guidelines Revision Committee to evaluate TG07, recognize new evidence, and conduct a multi-center analysis to revise the guidelines (TG13).Methods and materials We retrospectively analyzed 451 patients with acute cholecystitis from multiple tertiary care centers in Japan. All 451 patients were first evaluated using the criteria in TG07. The "gold standard" for acute cholecystitis in this study was a diagnosis by pathology. The validity of TG07 diagnostic criteria was investigated by comparing clinical with pathological diagnosis.Results Of 451 patients evaluated, a total of 227 patients were given a diagnosis of acute cholecystitis by pathological examination (prevalence 50.3 %). TG07 criteria provided a definite diagnosis of acute cholecystitis in 224 patients. The sensitivity of TG07 diagnostic criteria for acute cholecystitis was 92.1 %, and the specificity was 93.3 %. Based on the preliminary results, new diagnostic criteria for acute cholecystitis were proposed. Using the new criteria, the sensitivity of definite diagnosis was 91.2 %, and the specificity was 96.9 %. The accuracy rate was improved from 92.7 to 94.0 %. In regard to severity grading among 227 patients, 111 patients were classified as Mild (Grade I), 104 as Moderate (Grade II), and 12 as Severe (Grade III).Conclusion The proposed new diagnostic criteria achieved better performance than the diagnostic criteria in TG07. Therefore, the proposed criteria have been adopted as new diagnostic criteria for acute cholecystitis and are referred to as the 2013 Tokyo Guidelines (TG13). Regarding severity assessment, no new evidence was found to suggest that the criteria in TG07 needed major adjustment. As a result, TG07 severity assessment criteria have been adopted in TG13 with minor changes.

When a diagnosis of acute pancreatitis (AP) is made, fundamental medical treatment consisting of fasting, intravenous (IV) fluid replacement, and analgesics with a close monitoring of vital signs should be immediately started. In parallel with fundamental medical treatment, assessment of severity based on clinical signs, blood test, urinalysis and imaging tests should be performed to determine the way of treatment for each patient. A repeat evaluation of severity is important since the condition is unstable especially in the early stage of AP. At the time of initial diagnosis, the etiology should be investigated by means of blood test, urinalysis and diagnostic imaging. If a biliary pancreatitis accompanied with acute cholangitis or biliary stasis is diagnosed or suspected, an early endoscopic retrograde cholangiopancreatography with or without endoscopic sphincterotomy (ERCP/ES) is recommended in addition to the fundamental medical treatment. In mild cases, the fundamental medical treatment should be continued until clinical symptom is subsided with normal laboratory data. In cases with severe acute pancreatitis (SAP) referral should be considered to medical centers experienced in the treatment of SAP, and intensive care is recommended for preventing both organ failures and infectious complications. Hemodynamic stabilization with vigorous fluid resuscitation, respiratory support and antibiotics are the major parts of intensive care in the early period of SAP. Continuous hemodiafiltration (CHDF) and continuous regional arterial infusion (CRAI) of protease inhibitor and/or antibiotics may be effective to improve pathophysiology of AP especially in the early stage of the disease. In the late stage of AP, infectious complications are critical. If an infectious complication is suspected based on clinical signs, blood test and imaging, a fine needle aspiration (FNA) is recommended to establish a diagnosis. The accuracy of FNA is reported to be 89 ~ 100%. For patients with sterile pancreatitis, non-surgical treatment should be indicated. For patients with infected pancreatic necrosis, therapeutic intervention either by percutaneous, endoscopic, laparoscopic or surgical approach are indicated. The most preferred surgical intervention is necrosectomy, however, non-surgical treatment with antibiotics is still the treatment of choice if the general condition is stable. Necrosectomy should be performed as late as possible. For patients with pancreatic abscess, drainage is recommended.

Background The Tokyo Guidelines for the management of acute cholangitis and cholecystitis were published in 2007 (TG07) and have been widely cited in the world literature. Because of new information that has been published since 2007, we organized the Tokyo Guidelines Revision Committee to conduct a multicenter analysis to develop the updated Tokyo Guidelines (TG13).Methods/materials We retrospectively analyzed 1,432 biliary disease cases where acute cholangitis was suspected. The cases were collected from multiple tertiary care centers in Japan. The 'gold standard' for acute cholangitis in this study was that one of the three following conditions was present: (1) purulent bile was observed; (2) clinical remission following bile duct drainage; or (3) remission was achieved by antibacterial therapy alone, in patients in whom the only site of infection was the biliary tree. Comparisons were made for the validity of each diagnostic criterion among TG13, TG07 and Charcot's triad.Results The major changes in diagnostic criteria of TG07 were re-arrangement of the diagnostic items and exclusion of abdominal pain from the diagnostic list. The sensitivity improved from 82.8 % (TG07) to 91.8 % (TG13). While the specificity was similar to TG07, the false positive rate in cases of acute cholecystitis was reduced from 15.5 to 5.9 %. The sensitivity of Charcot's triad was only 26.4 % but the specificity was 95.6 %. However, the false positive rate in cases of acute cholecystitis was 11.9 % and not negligible. As for severity grading, Grade II (moderate) acute cholangitis is defined as being associated with any two of the significant prognostic factors which were derived from evidence presented recently in the literature. The factors chosen allow severity assessment to be performed soon after diagnosis of acute cholangitis.Conclusion TG13 present a new standard for the diagnosis, severity grading, and management of acute cholangitis.

Over the past decade, many studies have shown a significant association between the volume of hospital services and patient outcomes for a wide variety of medical conditions [1–3]. As regards acute pancreatitis, several population-based studies have shown higher hospital volume to be associated with better outcomes [4–6]. Especially, a lower mortality rate, shorter length of hospital stay and lower total costs had been shown with higher hospital volume. However, acute pancreatitis has a wide range of severity and mortality; especially severe acute pancreatitis has a high mortality rate and longer length of hospital stay. In clinical situations, several severity scoring systems have been used for judging the severity grading and making decisions for how to treat patients depending on the grading all over the world. Furthermore, various potentially effective treatments for acute pancreatitis, e.g. enteral nutrition, continuous hemofiltration, continuous regional arterial infusion, and endoscopic treatments, etc. are performed for severe acute pancreatitis. However, effectiveness and cost-performance analyses of those techniques have not been proven at this time. In addition, the mortality rate of each institution was not described, even for high volume centers. That is to say, a lot of clinicians have a great deal of concern about the volume–outcome relationship in order to perform effective treatments and decide referral patterns to improve mortality rates. In the current context, Professor Hamada et al. [7] are to be congratulated for performing the extremely large-scale study about clinical outcomes of acute pancreatitis based on the Japanese administrative database associated with the diagnostic procedure combination system (DPC). This is the first study to have successfully adjusted for baseline disease severity using an established scoring system to evaluate the volume–outcome relationship in acute pancreatitis. Unlike other analyses, this study focused on the hospital–volume relationship and severity of acute pancreatitis based on the Japanese Severity Scoring system [8]. Additionally, the researchers include adjustments for severity grading and assessment of the potential non-linear relationship between hospital volume and outcomes by means of restricted cubic spline (RCS) functions. As a result, the median length of hospital stay was 14 days (range 10–22 days) in Japan. Their analysis demonstrated that the median hospital volume was 22.4 (range 1–82 case/year), and higher hospital volume was associated with shorter length of stay (overall relationship p \ 0.001), however not evident in in-hospital mortality and total costs. Using the same Japanese DPC system database, Murata et al. [8] showed that increased hospital volume, which was categorized into tertiles, was significantly associated with decreased relative risk of in-hospital mortality in both patients with mild and severe acute pancreatitis. Meanwhile Professor Hamada et al. used the annual number of cases, not categorized, admitted to each individual hospital and mentioned that the correlation between the patients in the same hospital can be taken into account with using generalized estimating equations (GEE). Exactly this groundbreaking method was performed. So what is the key to have a better outcome and an effective utilization of medical resources? The clinical This comment refers to the article available at doi:10.1007/s00535013-0888-9.