3.1 Guide Features
A total of 186 related studies were retrieved, and some guidelines or consensuses were excluded for a variety of reasons. Finally, only seven guidelines or consensuses were included (Figure 1). The basic characteristics of the included guidelines are shown in Table 1. The publication date of the included guidelines ranged from 2014 to 2020. Two of the articles [2, 6] were from Italy, three [3,7,8] were from China, and the remaining two were from Japan and Canada [4,5]. One article [2] presented the original version of the guidelines, and the remaining six [3,4,5,6,7,8] presented updated versions that improved and extended the guidelines. Of the seven included guides, five guides used three grading systems to rate the level of evidence and the strength of the recommendation (Table 1); 3 [2,5,8] adopted the GRADE system, one [6] used the APACHE system, and one used the Delphi classification standard [7]. The evidence levels and recommended strength codes in the different rating systems vary widely.
3.2 Quality Evaluation of Acute Pancreatitis Guidelines
The guidelines were reviewed based on the latest English version of the AGREE II instrument (2017 edition) [9], a validated assessment tool designed to provide a framework for evaluating and monitoring clinical guidelines that can be used to measure and quantify guideline quality. The results of evaluating the methodological quality of the included guidelines using the AGREE II tool are shown below. Table 2 indicates that the Scope and Purpose domain and the Clarity and Expression domain reached a relatively significant median score of 71.62% (range 44.44% -87.50%) and 75.59% (range 23.61% -94.44%), respectively. The average scores of the Stakeholder Participation, Rigorousness of Development, and Editor Independence domains were roughly similar, 56.15% (range 33.33% -77.78%), 58.70% (range 43.22% -79.17%) and 54.17% (range 0.00% -97.92%), respectively. Unfortunately, the average score of the Applicability domain was the lowest at 16.67% (range 0.00% -34.38%). Finally, according to the scores, we provided overall recommendations. The detailed overall scores for each guideline are listed in Table 2. There were three guides with overall evaluation scores between 30% and 60% [4,6,8]. These guidelines fell into the recommended category, but they still need to be improved. Two guidelines had a total score of less than 30% [3,8], and so they could not be recommended. It is worth noting that there were two guidelines with relatively high scores (exceeding 60%) in each area except the Applicability domain [2,5],which were classified according to the recommendations of clinical practice developed by the World Society of Emergency Surgery (WSES) and the Japanese Society of Hepato-Biliary-Pancreatic Surgery, respectively. In this study, ICC values were used to evaluate the consistency of the four reviewers' assessments of the diagnosis guidelines for acute pancreatitis and were all found to exceed 0.90 (Table 2), indicating that the appraisers' evaluations were remarkably consistent.
3.3 Heterogeneity of recommendations and evidence for the diagnosis of acute pancreatitis
(1) Primary diagnosis of AP
Four guidelines [2,3,7,8] recommend abdominal pain as a reference indicator for the diagnosis of severe pancreatitis; the other three only mention the symptom. The recommendations of the three guidelines [3,7,8] for abdominal pain (sustained attacks, severe and acute episodes of epigastric pain usually radiating to the back) had a high similarity (80% -100%) to the reference recommendations. The cited levels of evidence were only grade 5 [2,7]. Six guidelines [2,3,4,5,7,8] recommend serum lipase activity (or amylase) at least three times the upper normal limit as a reference indicator for the diagnosis of severe pancreatitis, among which three guidelines make an explicit recommendation [4,5,8], while the remaining three guidelines only casually recommend it [2,3,7]. Five guidelines [3,4,5,7,8] recommending serum lipase activity (or amylase) at least three times the upper normal limit had a high degree of similarity (80% -100%) to the reference recommendation, and the reference level of evidence was up to grade 4 [4,8]. In six guidelines [1,2,3,4,5,7,8], the characteristics of abdominal imaging are recommended as reference indicators for the diagnosis of severe pancreatitis. Three of these guidelines make explicit recommendations [4,5,8], and the remaining three guidelines merely mentioned these characteristics in the content [2,3,7]. The recommendations of five guidelines [3,4, 5,7,8] for the characteristic findings from abdominal imaging had a high similarity (80% -100%) to the reference recommendation. The reference level of evidence, cited in only four of the guidelines, was a low grade 5 [2,4,5,7].
(2) Severity classification of AP
Five guidelines [2,3,4,7,8] recommend the revised Atlanta classification as a reference indicator for the diagnosis of severe pancreatitis, of which two guidelines make explicit recommendations [2,4] and the remaining three only mentions the classification in the content [3,7,8]. The recommendations of four guidelines [3,4,7,8] for the revised Atlanta classification had a high similarity (80% -100%) to the reference recommendation. The reference level of evidence cited in four of the guidelines was grade 5 [2,4,7,8]. Four guidelines [2,3,4,8] recommend CRP as a reference indicator for the diagnosis of severe pancreatitis, of which 3 guidelines make clear recommendations [2,4,8], and the remaining guideline only mentions CRP in the content [3]. The recommendations of two of the guidelines [4,8] for CRP have a high similarity to the reference recommendation(80% -100%). One guideline [3] demonstrated moderate similarity to the reference recommendation for CRP (40% -60%). The reference level of evidence cited in one set of guidelines was grade 5[2], and the reference level of evidence cited in another set of guidelines was a poor grade 5 [4]. Five guides [2,3,4,7,8] recommend the APACHE-II score as a reference indicator for the diagnosis of severe pancreatitis, three of which make explicit recommendations [2,4,7], and two of which only mention the score in the content [3,8]. The recommendations of four of the guidelines [3,4,7,8] for APACHE-II had a high similarity (80% -100%) to the reference recommendation. One guideline had a reference level of evidence of only grade 5 [7], two guidelines had only grade 4 [4,8], and one guideline had up to grade 2b [2].
(3) Etiological diagnosis of acute pancreatitis
Seven guidelines [2,3,4,5,6,7,8] recommend US/EUS as the reference index for the diagnosis of the cause of severe pancreatitis, of which three guidelines make explicit recommendations [2,4,8], and 4 guidelines only mention US/EUS in the content [3,5,6,7]. The recommendations of four guidelines [3,4,5,8] US/EUS had high similarity (80%-100%) to the reference recommendation, one guideline had moderate similarity [6] (40%-60%), and one guideline had low similarity [7] (20%- 40%). The reference levels of evidence for one set of guidelines were grades 1a, 2a, 3a, and 5. Six guidelines [2,3,4,5,6,8] recommend magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) as a reference indicator for the diagnosis of severe pancreatitis, four of which make explicit recommendations [2,4,5,6,8], while the remaining guideline only mentions MRI/MRCP in the content [3]. The recommendations for MRI/MRCP of these six guidelines had a high similarity (80% -100%) to the reference recommendation. Four guidelines provide reference levels of evidence, the highest of which was grade 2a.
Five guidelines [2,3,4,5,8] recommend endoscopic retrograde cholangiopancreatography (ERCP) as a reference indicator for the diagnosis of severe pancreatitis, of which three guidelines make explicit recommendations [4,5,8], while the remaining two guidelines only briefly mention ERCP in the content [2,3]. The ERCP recommendations of four studies had high similarity to the reference recommendation (80% -100%) [3,4,5,8]. Only two guidelines cited reference levels of evidence for ERCP, one with a grade 5 level of evidence [2], and the other with grade 1a [8].
(4) Diagnosis of AP comorbidities
CECT is recommended as a reference indicator for the diagnosis of severe pancreatitis in seven guidelines, four of which make explicit recommendations [4,5,6,8], and 3 guidelines only mention CECT in the content [2,3,7]. The recommendation of CECT in five guidelines [3,5,6,7,8] had high similarity to the reference recommendation (80% -100%), and that of one guide [4] had a moderate similarity to the reference recommendation(40% -60%). Only grade 5 evidence was cited in one guideline [2], grade 4 evidence is cited in one guideline [4], grade 2a in 1 guideline [5], and grade 3a in one guideline [6]. All seven guidelines recommend the collection of infections and fine needle aspiration (FNA) as a reference indicator for the diagnosis of severe pancreatitis after necrosis or infection, of which five guidelines make explicit recommendations [2,4,6,7,8], while the remaining two guidelines mention this procedure in the content [3,5]. Four guides have a high similarity to the reference recommendations of FNA (80%-100%). The level of evidence cited was grade 5 in one guideline [2], grade 4 in two guidelines [3,5], and grade 5 in two guidelines [6,8]. Four guidelines [3,5,6,8] recommend continuous abdominal pressure (IAP)> 20 mmHg for the diagnosis of abdominal syndrome (ACS) as a reference indicator for the diagnosis of severe pancreatitis, two of which make explicit recommendations [3,6], and the other two guidelines only mention this criterion [5,8]. Although guideline [2] was the standard literature for similarity evaluation, it did not mention the diagnosis of abdominal cavity syndrome (ACS) with continuous intra-abdominal pressure (IAP)> 20 mmHg, so no similarity scores could be obtained for this recommendation. One guideline cited a level of evidence of grade 1b [6], and one guideline cited a level of evidence of 3a [8].