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Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Liverpool Pancreatitis Research Group, Liverpool University Hospitals NHS Foundation Trust and Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
Liverpool Pancreatitis Research Group, Liverpool University Hospitals NHS Foundation Trust and Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, ChinaLiverpool Pancreatitis Research Group, Liverpool University Hospitals NHS Foundation Trust and Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Liverpool Pancreatitis Research Group, Liverpool University Hospitals NHS Foundation Trust and Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
Correspondence: Wenhua He, Pancreatic Disease Centre, Department of Gastroenterology, First Affiliated Hospital of Nanchang University, 17 Yong wai zheng Street, Nanchang, Jiangxi Province, 330006, China.
Correspondence: Wei Huang, Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Centre, West China Hospital, Sichuan University, No. 37 Wannan Guoxue Alley, Chengdu 610041, Sichuan Province 610041, China.
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Correspondence: Qing Xia, Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Centre, West China Hospital, Sichuan University, No. 37 Wannan Guoxue Alley, Chengdu 610041, Sichuan Province 610041, China.
Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
Early prediction of persistent organ failure (POF) is important for triage and timely treatment of patients with acute pancreatitis (AP).
Methods
All AP patients were consecutively admitted within 48 h of symptom onset. A nomogram was developed to predict POF on admission using data from a retrospective training cohort, validated by two prospective cohorts. The clinical utility of the nomogram was defined by concordance index (C-index), decision curve analysis (DCA), and clinical impact curve (CIC), while the performance by post-test probability.
Results
There were 816, 398, and 880 patients in the training, internal and external validation cohorts, respectively. Six independent predictors determined by logistic regression analysis were age, respiratory rate, albumin, lactate dehydrogenase, oxygen support, and pleural effusion and were included in the nomogram (web-based calculator: https://shina.shinyapps.io/DynNomapp/). This nomogram had reasonable predictive ability (C-indexes 0.88/0.91/0.81 for each cohort) and promising clinical utility (DCA and CIC). The nomogram had a positive likelihood ratio and post-test probability of developing POF in the training, internal and external validation cohorts of 4.26/31.7%, 7.89/39.1%, and 2.75/41%, respectively, superior or equal to other prognostic scores.
Conclusions
This nomogram can predict POF of AP patients and should be considered for clinical practice and trial allocation.
Introduction
Acute pancreatitis (AP) has a spectrum of severity ranging from mild to critical.
Early prediction is also important in the research setting, where the accurate allocation of patients into trial arms based on predicted severity is important for testing treatments for AP. The key determinants of AP severity are organ failure and infected pancreatic necrosis.
are not sufficiently accurate for decision making in individual patients. The ideal predictor of POF would be applied on patient admission and within 24 h of the onset of symptoms. It would be cost-effective, easy to use and have an accuracy between 95 and 100%. Considerable progress has been made in identifying serum biomarkers to stratify early risk and severity in patients with AP.
However, due to their rapid time-course changes in serum concentration, non-specificity, cost, complexity, and suboptimal accuracy, none of these biochemical biomarkers have been adopted into routine clinical practice. In recent years, different nomograms have been applied for predicting severity and mortality,
Early prediction of in-hospital mortality in acute pancreatitis: a retrospective observational cohort study based on a large multicentre critical care database.
Predictors of outcome of percutaneous catheter drainage in patients with acute pancreatitis having acute fluid collection and development of a predictive model.
Early prediction of in-hospital mortality in acute pancreatitis: a retrospective observational cohort study based on a large multicentre critical care database.
that used a nomogram to predict severity and mortality, 3 studies used online Critical Care Database (Medical Information Mart for Intensive Care III database [MIMIC-III],
Early prediction of in-hospital mortality in acute pancreatitis: a retrospective observational cohort study based on a large multicentre critical care database.
None of the 4 studies reported the duration of symptoms prior to hospital admission. No study to date has used training and validation cohorts to develop a nomogram to predict POF in AP patients.
Table 1Summarize of the present developed nomograms in AP
Early prediction of in-hospital mortality in acute pancreatitis: a retrospective observational cohort study based on a large multicentre critical care database.
Predictors of outcome of percutaneous catheter drainage in patients with acute pancreatitis having acute fluid collection and development of a predictive model.
Intra-abdominal pressure, APACHE II score, CTSI, ICU admission, and severity grade
417
0.99
294
0.98
SAP, severe acute pancreatitis; MIMIC-III, Medical Information Mart for Intensive Care III; NA, not available; ALT, alanine aminotransferase; RDW, red cell distribution width; BUN, blood urea nitrogen; WBC, white blood cell count; SCR, serum creatinine; BISAP, Bedside Index of Severity in Acute Pancreatitis; SOFA, Sequential Organ Failure Assessment; SIRS, Systemic Inflammatory Response Syndrome; ICU, intensive care unit; eICU-CRD, eICU Collaborative Research Database; APACHE, Acute Physiology, Age, and Chronic Health Evaluation; TBIL, total bilirubin; OASIS, Outcome and Assessment Information Set; NE%, neutrophil ratio; LYMPH%, lymphocyte Ratio; eosinophil ratio, EO%; GCSI, Gastroparesis Cardinal Symptom Index; LDL-C, low density lipoprotein-cholesterol; PCD, percutaneous catheter drainage; CTSI, computed tomography severity index.
The aim of this study was (1) to develop and validate a nomogram for predicting POF on admission in patients with AP, and (2) to compare the performance of the nomogram with conventional prognostic scores for predicting POF.
for observational studies. The study protocol was approved by respective Institutional Review Board in two tertiary hospitals. Data were obtained from two AP cohorts in West China Hospital of Sichuan University (WCH/SCU; Chengdu). The training cohort was from a retrospective dataset from 1st July 2009 to 30th June 2013.
Early rapid fluid therapy is associated with increased rate of noninvasive positive-pressure ventilation in hemoconcentrated patients with severe acute pancreatitis.
The external validation cohort was from a prospective dataset from The First Affiliated Hospital of Nanchang University (Nanchang) from 1st January 2005 to 31st December 2012.
A study on the etiology, severity, and mortality of 3260 patients with acute pancreatitis according to the revised Atlanta classification in jiangxi, China over an 8-year period.
(2) age >18 and ≤80 years old, and (3) duration of abdominal pain from onset to admission ≤48 h, (4) data to calculate conventional prognostic scores within 6 h of admission.
The exclusion criteria were (1) patients admitted to another hospital first and then transferred, (2) patients re-admitted during the same episode of AP, (3) patients with an etiology related to chronic pancreatitis, pancreatic neoplasia, pancreatic trauma, or pregnancy, (4) advanced pulmonary, cardiac, renal diseases (chronic kidney disease stage 4–5), liver cirrhosis (modified Child–Pugh grade 2–3) or malignancy, and (5) if the nomogram could not be completed because of missing data.
Definitions, variables, and outcome measures
Data collection: Experienced doctoral students and resident doctors specializing in management of AP were stringently trained for data collection according to pre-defined proforma and standard operating procedures in both centers. Each proforma was checked and signed off by attending or more senior doctors. The data collected on admission included age, gender, data for Charlson co-morbidity index, and duration of abdominal pain prior to admission. Vital signs, laboratory parameters (indices of routine blood, liver and renal function, myocardial enzymes, blood lipids and glucose, electrolyte levels and etc.), details of treatment (especially use of oxygen support, vasopressors, dialysis, antibiotic, and steroids), surgical interventions, and clinical outcomes were also recorded.
Presence of pleural effusion that were mostly obtained from nonenhanced computed tomography scan on admission. Patients without overt symptoms of pleural effusion (dyspnea, cough, and occasionally sharp, non-radiating, pleuritic chest pain) were not referred to having X-ray or CT scan in up to 10% of overall patients and these patients were considered as pleural effusion free.
Etiology
Hypertriglyceridemia as the etiology was defined as admission serum triglyceride (TG) level >11.3 mmol/l (1000 mg/dl) or TG > 5.65 mmol/l (500 mg/dl) with lipemic serum when other causes have been ruled out.
Biliary etiology was considered if gallstones or biliary sludge was present on radiological imaging or had an admission alanine aminotransferase level of over three times the upper limit of normal.
Mortality was recorded during the index admission or at 3 months of follow up for those who were automatically discharged with persistent multiple organ failure and had high possibility of death. Length of hospital stay were recorded for the index hospitalization.
Prognostic scores
The prognostic scores that were compared with the nomogram in this study were National Early Warning Score (NEWS),
These were all calculated on admission (or within 6 h of admission in rare cases).
Statistical analysis
Continuous variables were expressed as median with 25th-75th percentile and were compared by Mann–Whitney U test (2 groups) or Kruskal–Wallis H test (3 groups). Categorical data were reported as number with percentage and were compared by means of χ2 or Fisher's exact test.
Independent risk factors for POF were identified and assessed significance of each by univariate logistic regression analysis in the training cohort. All variables significantly associated with POF were candidates for stepwise multivariate analysis, the results of which were used to formulate a nomogram. The predictive performance of the nomogram was measured by concordance index (C-index) and calibration with 1000 bootstrap samples to decrease the overfit bias.
The area under curve (AUC) of the receiver operating characteristic (ROC) curves with 95% confidence intervals (CI) was calculated for potential predictors. An AUC of 0.5–0.7 was taken to represent no significant discrimination, 0.7 to 0.8 acceptable, 0.8 to 0.9 excellent, and >0.9 outstanding.
The optimum cut-off for each predictor was determined by the ROC curve. The sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were calculated by clinical decision analysis. A positive likelihood ratio is the probability that a positive test would be expected in a patient divided by the probability that a positive test would be expected in a patient without the endpoint of interest (e.g. POF). A negative likelihood ratio is the converse and if < 0.1 effectively rules out the endpoint. The post-test probabilities for each predictor were derived from the PLR (and NLR), using the pre-test probability of the particular endpoint from the relevant cohort and the standard likelihood ratio nomogram.
The analyses were performed using IBM SPSS Statistics V26.0 software (SPSS, IBM Corp; Armonk, New York, USA) and R software version 4.0.4 (http://www.Rproject.org). Two-tailed P value with statistical significance set at < 0.05 was used for all tests.
Results
Patient characteristics
There were 816, 398, and 880 eligible patients in the training, internal validation and external validation cohorts, respectively. The demographic and clinical outcome profiles are outlined in Table 2 and OnlineSupplementary Tables S1a–c. These results are similar to previous published studies.
Early rapid fluid therapy is associated with increased rate of noninvasive positive-pressure ventilation in hemoconcentrated patients with severe acute pancreatitis.
A study on the etiology, severity, and mortality of 3260 patients with acute pancreatitis according to the revised Atlanta classification in jiangxi, China over an 8-year period.
The median age was 45 years old and about 70% patients were male in both training and internal validation cohorts, while median age was 50 years old and 61% patients were male in the external validation cohorts. Hypertriglyceridemia (32.7% and 42%) was the most common etiology in the training and internal validation cohorts. Biliary (57.5%) was the most common etiology in the external validation cohort.
Table 2Baseline characteristics and clinical outcomes in training and validation cohorts
Variables
Training cohort
Validation cohorts
n = 816
(Internal) n = 398
(External) n = 880
Demographics
Age, years∗
45 (37–55)
45 (38–51)
50 (41–62)
Male
568 (69.6)
273 (68.6)
533 (60.6)
Charlson comorbidity index∗
1 (0–1)
1 (0–2)
0 (0–0)
Etiology
Biliary
230 (28.2)
78 (19.6)
506 (57.5)
Hypertriglyceridemia
267 (32.7)
167 (42.0)
184 (20.9)
Alcohol
30 (3.7)
31 (7.8)
61 (6.9)
Unknown or others
289 (35.4)
122 (30.7)
129 (14.7)
Time to admission, hours∗
12 (7–24)
15 (9–24)
NA
Clinical outcomes
Persistent organ failure
80 (9.8)
30 (7.5)
178 (20.2)
Respiratory
77 (9.4)
30 (7.5)
169 (19.2)
Circulatory
14 (1.7)
2 (0.5)
12 (1.4)
Renal
10 (1.2)
3 (0.8)
28 (3.2)
Need for HDU/ICU
59 (7.2)
29 (7.3)
168 (19.1)
Local complication
Acute peripancreatic fluid collection
163 (20.0)
119 (29.9)
332 (37.7)
Acute necrotic collection
59 (7.2)
55 (13.8)
204 (23.2)
Major infection
45 (5.5)
20 (5.0)
53 (6.0)
Infected pancreatic necrosis
12 (1.5)
9 (2.3)
36 (4.1)
Bacteremia
15 (1.8)
6 (1.5)
13 (1.5)
Lung
35 (4.3)
9 (2.3)
18 (2.0)
Necrosectomy
14 (1.7)
13 (3.3)
17 (1.9)
Mortality
10 (1.2)
4 (1.0)
20 (2.3)
RAC
Mild
508 (62.3)
190 (47.7)
328 (37.3)
Moderately severe
228 (27.9)
178 (44.7)
374 (42.5)
Severe
80 (9.8)
30 (7.5)
178 (20.2)
Length of hospital stay (days)∗
9 (6–13)
8 (6–11)
8 (6–13)
NA, not available; HDU, high dependency unit; ICU, intensive care unit; RAC, revised Atlanta classification.
Values in parentheses are percentages unless indicated otherwise ∗values are median with 25th-75th percentile.
Candidate variables for the nomogram were drawn from demographic, vital signs, blood and biochemical tests, on admission. The independent prognostic factors for POF after univariate and multivariate logistic regression analysis were age (OR 1.03 [95% CI 1.01–0.05]; P = 0.01), respiratory rate (1.25 [1.10–1.42]; P = 0.001), albumin (0.92 [0.87–0.98]; P = 0.013), lactate dehydrogenase (LDH; 1.002 [1.000–1.003]; P = 0.036), oxygen support (5.17 [2.91–9.20]; P < 0.001), and pleural effusion (3.61 [1.97–6.61]; P < 0.001) (Table 3). These variables were then used to construct the predictive nomogram (Fig. 1a). The total score was calculated as: ([age × 0·3224] – 4.8358]) + ([respiratory rate × 2.5] – 25]) + (43.518 – [0·7912 × albumin]) + (LDH × 0.0196) + 15.521 (if oxygen support) + 12.551 (if exist of pleural effusion). To facilitate the clinical application of our findings, we developed a mobile terminal-based calculator (https://shina.shinyapps.io/DynNomapp/) of the predictive nomogram (Fig. 1b and c).
Table 3Univariate and multivariate logistic regression analysis with stepwise variable selection
Figure 1Nomogram for predicting POF in patients with AP and dynamic web-based calculator. Patient prognostic values are located on the axis of each variable; a line is then drawn upwards at a 90° angle to determine the number of points for that particular variable. The sum of these numbers is located on the total points axis, and a line is drawn at a 90° angle downward to the “Predicted SAP” axis to determine the likelihood of POF (a). Alternatively, POF rate can be ascertained from the online calculator with 95% CI in both graphical (b) and numerical (c) summary
In the training cohort there was good concordance (C-index) between predicted POF and actual POF at 0.88 (Fig. 2a) and shown by the calibration curve (Fig. 2b). The C-index was 0.91 for the internal validation cohort (Figure 2c and d) and 0.81 for the external validation cohort (Figure 2e and f) compared with the training cohort.
Figure 2Assessment of the nomogram in all three cohorts. The accuracy of the model was determined using AUC analysis and the distribution of the predicted probabilities presented by calibration curve for cohorts of the training (a, b), internal validation (c, d), and external validation (e, f)
The nomogram of training cohort (Fig. 3a and b), internal validation cohort (Fig. 3c and d), and external validation cohort (Fig. 3e and f) exhibited better or equal clinical utility (DCA) with the other prognostic scores and had good clinical net benefits (CIC) for the identification of SAP patients. Of particular note, the nomogram outperformed all other indices in the internal validation cohort suggesting that it could help clinicians to obtain maximum benefit when making clinical decisions as it showed more benefit than the extreme situation of diagnosing POF in all patients or none.
Figure 3Clinical utility of the nomogram. The DCA and CIC of the nomogram for predicting POF in cohorts of training (a, b), internal validation (c, d), and external validation (e, f)
Prediction of POF, major infection, and mortality by nomogram
Prediction of POF
The pre-test probability of POF in the training, internal validation and external validation cohorts was 9.8% (80/816), 7.5% (30/398) and 20.2% (178/880) patients, respectively (Table 2).
The nomogram had a positive likelihood ratio and post-test probability of developing POF in the training, internal validation and external validation cohorts of 4.26 and 31.7% (259/816), PLR 7.89 and 39.1% (156/398) and PLR 2.75 and 41% (361/880) patients, respectively (Table 4).
Table 4Predictive value of the nomogram and clinical prognostic scores for persistent organ failure
AUC
P value
Cut-off
Sensitivity (%)
Specificity (%)
PLR
NLR
Post_Prob_Pos (%)
Post_Prob_Neg (%)
Training cohort(9.8% pre-test probability)
Nomogram
0.88 (0.86–0.91)
<0.001
91.2
78.8
81.5
4.26
0.26
31.7
2.8
NEWS
0.85 (0.82–0.87)
<0.001
4
66.3
88
5.54
0.38
37.6
4
BISAP
0.89 (0.87–0.91)
<0.001
2
78.8
89.1
7.24
0.24
44.0
2.5
APACHE II
0.79 (0.76–0.82)
<0.001
6
61.3
83
3.61
0.47
28.2
4.9
SIRS
0.84 (0.81–0.86)
<0.001
2
91.3
74.6
3.59
0.12
28.1
1.3
Glasgow
0.75 (0.72–0.78)
<0.001
2
61.3
78.8
2.89
0.49
23.9
5.1
SOFA
0.87 (0.84–0.89)
<0.001
1
85
81.2
4.53
0.18
33.0
1.9
Validation cohort
Internal validation (7.5% pre-test probability)
Nomogram
0.91 (0.88–0.94)
<0.001
79.2
90
88.6
7.89
0.11
39.1
0.9
NEWS
0.79 (0.75–0.83)
<0.001
4
70.0
75.0
2.80
0.40
18.5
3.1
BISAP
0.75 (0.71–0.79)
<0.001
2
46.7
91.9
5.72
0.58
31.7
4.5
APACHE II
0.66 (0.61–0.71)
0.005
6
36.7
89.4
3.46
0.71
21.9
5.4
SIRS
0.68 (0.63–0.72)
<0.001
2
70.0
61.4
1.81
0.49
12.8
3.8
Glasgow
0.69 (0.64–0.73)
<0.001
3
46.7
80.7
2.42
0.66
16.4
5.1
SOFA
0.73 (0.68–0.77)
<0.001
2
63.3
75.8
2.62
0.48
17.5
3.7
External validation (20.2% pre-test probability)
Nomogram
0.81 (0.79–0.84)
<0.001
69.4
79.8
70.9
2.75
0.29
41
6.7
NEWS
0.76 (0.73–0.79)
<0.001
5
62.4
78.6
2.92
0.48
42.5
10.8
BISAP
0.75 (0.72–0.78)
<0.001
2
53.4
84.3
3.41
0.55
46.3
12.3
APACHE II
0.75 (0.72–0.78)
<0.001
9
56.2
80.8
2.92
0.54
42.6
12.1
SIRS
0.73 (0.70–0.76)
<0.001
2
68.0
69.2
2.21
0.46
35.9
10.5
Glasgow
0.78 (0.75–0.81)
<0.001
3
59.6
82.5
3.4
0.49
46.3
11.1
SOFA
0.80 (0.77–0.83)
<0.001
2
63.5
85.0
4.24
0.43
51.8
9.8
AUC, area under curve; PLR, positive likelihood ratio; NLR, negative likelihood ratio; Post_Prob_Pos, post-test probability of a positive test; Post_Prob_Neg, post-test probability of a negative test; NEWS, National Early Warning Score; BISAP, Bedside Index for Severity in Acute Pancreatitis; APACHE II, Acute Physiology and Chronic Health Examination II; SIRS, Systemic Inflammatory Response Syndrome; SOFA, Sequential Organ Failure Assessment.
The nomogram had a negative likelihood ratio and post-test probability of not developing POF in the training, internal validation and external validation cohorts of 0.26 and 2.8% (23/816), PLR 0.11 and 0.9% (4/398) and PLR 0.29 and 6.7% (59/880) patients, respectively (Table 4).
Comparison with other prognostic systems for POF
Training Cohort: Comparing with the other prognostic scores, the nomogram had the second highest AUC (AUC 0.88 [0.86–0.91]; the AUC for BISAP was 0.89 [0.87–0.91]. BISAP had the highest predictive value (AUC 0.89 [0.87–0.91], PLR 7.24) for POF compared with the other indices (Table 4; upper panel) and followed by the nomogram (AUC 0.88 [0.86–0.91], PLR 4.26), both higher than APACHE II (0.79 [0.76–0.82], PLR 3.61) and Glasgow (0.75 [0.72–0.78], PLR 2.89) (P < 0.05, Online Supplementary Table S2) in training cohort.
Internal validation cohort: The nomogram showed the best predictive value (AUC 0.91 [0.88–0.94], PLR 7.89, Table 4; middle panel) in internal validation cohort and higher than all other clinical scoring systems (P < 0.05; Online Supplementary Table S2), followed by NEWS (0.79 [0.75–0.83], PLR 2.80) and BISAP (0.75 [0.71–0.79], PLR 5.72). In addition, the NLR (0.11) of the nomogram ranked the best among all the comparative indices, with the lowest post-test probability of not being POF (0.9%) indicating a high negative prediction value.
External validation cohort: The nomogram also ranked the top AUC (0.81 [0.79–0.84]), lowest NLR (0.29) and post-test probability of not being POF (6.7%) among all the indices in the external validation cohort (Table 4; lower panel), with the AUC higher than NEWS, BISAP, APACHE II and SIRS (P < 0.05; Online Supplementary Table S2).
Subgroup analyses compared predictive value of the nomogram on POF between different causes of AP patients. The nomogram showed no significant difference in predictive values for predicting POF in both hypertriglyceridemia and non-hypertriglyceridemia (biliary, alcohol and others) patients in all three cohorts (Table 5).
Table 5Accuracy of nomogram in predicting POF between hypertriglyceridemia and non-hypertriglyceridemia associated-acute pancreatitis patients
Etiology
Pre-test probability
AUC
P value
Cut-off
Sensitivity (%)
Specificity (%)
PLR
NLR
Post_Prob_Pos (%)
Post_Prob_Neg (%)
P value
Training cohort
HTG
12.4%
0.89 (0.84–0.92)
<0.001
71.7
100
62.0
2.63
0.0
27.0
0.0
0.998
Non-HTG
8.56%
0.89 (0.86–0.91)
<0.001
91.2
83.0
78.7
3.89
0.22
26.7
2.0
Validation cohort
Internal validation cohort
HTG
8.98%
0.91 (0.86–0.95)
<0.001
82.5
93.3
90.8
10.13
0.07
50.0
0.7
0.970
Non-HTG
6.49%
0.92 (0.87–0.95)
<0.001
79.2
86.7
90.3
8.91
0.15
38.2
1.0
External validation cohort
HTG
25%
0.86 (0.80–0.91)
<0.001
76.3
76.1
82.6
4.37
0.29
59.3
8.8
0.115
Non-HTG
19%
0.80 (0.77–0.83)
<0.001
69.6
77.3
70.9
2.66
0.32
38.3
7.0
POF, persistent organ failure; AUC, area under curve; PLR, positive likelihood ratio; NLR, negative likelihood ratio; Post_Prob_Pos, post-test probability of a positive test; Post_Prob_Neg, post-test probability of a negative test; HTG, hypertriglyceridemia.
There was 5.5% (45/816), 5.0% (20/398) and 6.0% (53/880) had infection in the training, internal and external validation cohorts, respectively. In the training cohort, the accuracy of these predictors was generally low with BISAP (0.75 [0.72–0.78], PLR 4.29) having the highest predictive value compared with the other indices in training cohort (Online Supplementary Table S3; upper panel), but there was no statistical difference between any of them (Online Supplementary Table S2). In both the internal and external validation cohorts, the nomogram showed the best predictive value (highest AUC 0.78 [0.73–0.82]/0.80 [0.77–0.83]; lowest NLR 0.47/0.22; lowest post-test probability of not being major infection 2.4%/1.4%; Online Supplementary Table S3; middle and lower panels).
Prediction of mortality
There was 1.2% (10/816), 1.0% (4/398) and 2.3% (20/880) mortality in the training, internal validation and external validation cohorts, respectively. All the deaths were from patients with POF in the three cohorts (12.5%, 13.3% and 11.2%; Online Supplementary Tables S1a–c). In both the training and external cohorts, the nomogram (AUC 0.88 [0.85–0.90], 0.89 [0.87-0.91]) showed the equivalent predictive values for mortality with most of the clinical scoring systems (Online Supplementary Table S4). In the internal validation cohort, the nomogram had the highest predictive values (0.99 [0.98–1.00], PLR 32.8, NLR 0.26) for mortality, followed by BISAP (0.95 [0.92–0.97], PLR 9.85), and NEWS (0.90 [0.86–0.93], PLR 29.6, NLR 0.26), all higher than the remaining clinical scores (Online Supplementary Table S4).
Data integrity
Since there was substantial amount of missing data, we assessed whether the patients included in all cohorts were different from those who were excluded due to missing data. There were no significant differences in age, hypertriglycedemic etiology, persistent organ failure, major infection, and mortality (Online Supplementary Table S5).
Discussion
In this study, we developed and validated a mobile terminal-based nomogram for predicting POF, major infection, and mortality using six independent prognostic factors (age, respiratory rate, albumin, LDH, oxygenation, and pleural effusion) that readily available on admission. This nomogram was found to be superior with the both internal and external validation cohort compared with other prognostic scores recommended for clinical use for predicting POF and major infection. Subgroup analysis comparing hypertriglyceridemia and non-hypertriglyceridemia etiology did not significantly change the predictive values of the nomogram for predicting POF, indicating its suitability for heterogenous etiologies. As POF is the diagnostic criteria for SAP, this nomogram is recommended for routine clinical use to predict SAP on admission or to rule it out (validation NLR 0.11/0.29). Therefore, these findings encourage the use of the simple-to-use web-based nomogram before new markers are developed and introduced in our settings. The consecutive nature of patient recruitment and short time from onset of pain to admission, stringently applied in two large different Chinese centers, adds strength to these conclusions.
Age is recognized as an individual risk factor for increased severity of AP and has been used by several prognostic scores
carried out a retrospective study in 84,713 patients with a first-attack AP. They found that the 65 to 75 age group, and age >75 are strong predictors of early death with an odds ratio (OR) of 2.6 and 5.2, respectively. Similar findings also applied to patients with two chronic comorbidities (OR: 3.5) or ≥ 3 comorbidities (OR: 7.4). Moreover, the mortality rate was only 0.1% (14/14,280) for younger patients (age <55) without chronic comorbidities compared to 5.9% (701/24,852) for elderly patients (age >64) with ≥3 comorbidities in the first 14 days. In addition, they showed that recent cancer, heart failure, and renal and liver diseases are strongly correlated with outcomes. Further, in acute interstitial AP, which is known to have low mortality, the Charlson comorbidity index was strongly associated with adverse clinical outcomes.
Because of the significant impact of the degree and number of comorbidities on clinical outcomes, we therefore excluded patients with advanced (end-stage) comorbidities with an emphasizing on assessing the intrinsic prognostic factors for AP severity.
Hypoalbuminemia occur in critically ill patients due to several factors including dilution from resuscitation, increased interstitial loss, altered liver function, and catabolic nutritional state.
It is strongly associated with poor clinical outcomes in acutely ill patients and it has also been shown to independently associated with POF and mortality in AP patients.
has recently found that albumin dropped rapidly in AP patients with multiple organ failure resulting in unregulated capillary leak with continued loss of larger plasma proteins. In contrast, the plasma albumin levels only dropped slightly in patients without multiple organ failure who tended to recover quickly unless they develop complications (infected pancreatic necrosis or sepsis). The therapeutic effect of albumin in inflammatory states is not only by affecting plasma volume dilation, but also by regulating inflammation and oxidative stress.
Elevated lactate may serve as a protective mechanism and has been shown to reduce Toll-like receptor and inflammasome-mediated pancreatic and liver injury via its receptor GPR81. LDH can reversibly catalyze the oxidation of lactate to pyruvate and has been employed by Ranson, Glasgow, Japanese Severity Score,
Early prediction of in-hospital mortality in acute pancreatitis: a retrospective observational cohort study based on a large multicentre critical care database.
the early recognition of respiratory dysfunction is considered important. Our results showed a positive association between the development of POF and an increased respiratory rate or requirement for oxygen support on admission. Therefore, both respiratory rate and oxygen support have been adopted in NEWS
Our results showed that pleural effusion (odds ratio: 3.61 95%CI 1.97–6.6, P < 0.001) was an independent predictor for SAP, consistent with a previous study.
In our univariate analysis before establishing the predictive nomogram, we also found white blood cell count, glucose, urea (or blood urea nitrogen), creatinine, and ionized calcium were independent individual prognostic factors for POF, consistent with previously published literature.
However, when these parameters were fitted into our multiple logistic regression model, they only had negligible impact on the final nomogram. Unlike most previously published studies included high proportion of SAP patients, we used a training consecutive cohort constituted only up to 10% of SAP patients which may partially explain different weights of individual prognostic factors in varied epidemiology situations. For example, three of the four existing predictive nomograms for AP severity were conducted in the ICU settings which cannot be generalizable for emergence departments or general wards where patients are primarily admitted.
Some of the six independent prognostic factors of our nomogram are included as part of NEWS (respiratory rate and oxygen support) and BISAP (age, respiratory rate, and pleural effusion), the two that we found had justifiable good predictive values for POF in both our training and internal validation cohorts. However, the nomogram was simpler than BISAP and more AP-specific than NEWS to quantitatively predict clinical outcomes in a personalized way. In addition, we validated the nomogram in another Chinese tertiary hospital with the etiological composition different from ours. The results showed that the nomogram with stable clinical applicability in both AP cohorts with hypertriglyceridemia (internal validation) or biliary (external validation) as the main etiology, adding strength to its applicability.
Our study also has some limitations. Firstly, excluding missing data may contribute to varied accuracy of the nomogram. However, we found majority of the key parameters of baseline and outcomes, albeit not all (i.e. gender and length of hospital stay), were similar between those included and those with missing data in all cohorts. Secondly, the nomogram model was developed mainly based on the variables that were easy to get in our retrospective sets, but did not include other factors that may influence the precision of the model. For example, the oxygenation index was not included in our analysis because only paucity data were available. In a most recent study,
the authors found that oxygenation index had low prognostic power (AUC 55.3%) for acute respiratory distress syndrome. Thirdly, the nomogram did not have specific markers for circulatory and renal failure. The reasons for this may be attributed to low incidence of circulatory and renal failure of the study population and at the early disease stage respiratory failure commonly precedes other organ failures.
In the last, the lack of international validation may limit the extrapolation and generalizability of the nomogram.
Conclusions
Our nomogram based on six readily available factors accurately predicted POF on admission in patients with AP. This nomogram can be routinely used for early AP severity prediction in our clinical practice if further validated in multiple center studies.
Authors’ contributions
QX, WH, and WHe obtained funding, and concepted, designed and supervised the study. NS collected, analyzed all retrospective and prospective data of Chengdu center, and drafted the manuscript. XZ collected and analyzed all retrospective data. WHe, LX, YZ, and NL provided and analyzed external validation datasets. LL, WC, LY, XY (Xinmin Yang) and RZ supported collecting data. PZ assisted data analysis. LD, TJ, ZL and KJ audited data quality. GJ and XY (XiaonanYang) supervised the patients’ treatment. WH and QX designed, TW and PS assisted, RS reviewed the proforma and e-database. VKS, RS, and JAW had important intelligence input. WH and JAW critically revised the manuscript. All authors read and approved the final manuscript.
Ethics approval and consent to participate
This study was approved by the Institutional Review Board of West China Hospital of Sichuan University and The First Affiliated Hospital of Nanchang University.
Consent for publication
All authors have provided consent for publication of the manuscript.
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Acknowledgements
The authors thank all the participants and attending physicians for their contributions. This study was supported by NZ-China Strategic Research Alliance 2016 Award (China: 2016YFE0101800, QX, TJ, WH and LD; New Zealand: JAW); Key Research and Development Program of Science and Technology Department of Sichuan Province (2020YFS0235, NS; 2019YFS0259, XZ); National Natural Science Foundation of China (81973632, WH; 81774120, QX; 81860122, WHe); and National Institute for Health Research (NIHR) Senior Investigator Award (RS).
Conflicts of interest
None to declare.
Appendix A. Supplementary data
The following are the Supplementary data to this article:
Early prediction of in-hospital mortality in acute pancreatitis: a retrospective observational cohort study based on a large multicentre critical care database.
Predictors of outcome of percutaneous catheter drainage in patients with acute pancreatitis having acute fluid collection and development of a predictive model.
Early rapid fluid therapy is associated with increased rate of noninvasive positive-pressure ventilation in hemoconcentrated patients with severe acute pancreatitis.
A study on the etiology, severity, and mortality of 3260 patients with acute pancreatitis according to the revised Atlanta classification in jiangxi, China over an 8-year period.