New markers in predicting the severity of acute pancreatitis in the emergency department: Immature granulocyte count and percentage.

BACKGROUND: Acute pancreatitis (AP) may vary in severity, from mild, self-limiting pancreatic inflammation to rapidly progressive life-threatening clinical course. If the severity of AP can be predicted early and treated quickly, it may lead to a decrease in morbidity and mortality rates. There?fore, we aimed to investigate the clinical utility of immature granulocyte count (IGC) and IGC percentage (IG%) in showing the severity of AP in this study.
METHODS: Two hundred and twenty-seven patients who were admitted to our emergency department and diagnosed with AP between March 1 and September 30, 2019, were included in the study. The patients were divided into two groups as mild and severe AP (MAP and SAP) according to the severity of the disease. Demographic characteristics of the patients, disease etiology, disease severity, and inflammation markers [white blood cell count (WBC), IGC, IG%, neutrophil-lymphocyte ratio (NLR), and C-reactive protein (CRP)] were recorded. Differences between the groups were statistically analyzed.
RESULTS: Of the patients included in the study, 183 (80.7%) were in the MAP group and 44 (19.3%) were in the SAP group. The mean WBC, NLR, CRP, IGC, and IG% levels were significantly higher in the SAP group compared to the MAP group. The power of IGC and IG% in predicting SAP was higher than other inflammation markers (WBC, NLR, and CRP) [(AUC for IGC: 0.902; sensitivity: 78.2%; specificity: 92.8%); (AUC for IG%: 0.843; sensitivity: 72.7%; specificity: 84.6%)].
CONCLUSION: IGC and IG% show the severity of AP more effectively than WBC, NLR, and CRP, which are traditional inflammation markers.

Introduction

Acute pancreatitis (AP) is a very common gastrointestinal disease in the emergency department (ED) with an annual incidence of 5–100 per 100,000 in Europe.[1] The severity of the disease may vary, from a mild, self-limiting pancreatic inflammation to rapidly progressive life-threatening clinical course that may cause multiple organ failure.[2] The overall mortality rate is 2.1%, but this rate increases to about 17% in severe AP (SAP).[3] If the severity of AP can be predicted early and treated quickly, it may lead to a decrease in morbidity and mortality rates.[4] Therefore, there is a need for biomarkers that can quickly and reliably predict AP severity. Although various inflammation markers (C-reactive protein [CRP], interleukin-6 neutrophil–lymphocyte ratio [NLR], platelet–lymphocyte ratio [PLR], and red blood cell distribution width (RDW) to platelet ratio, procalcitonin) and scoring systems (PANC3, Ranson, Acute Physiology and Chronic Health Evaluation [APACHE] II score, and Atlanta) have been developed for this purpose, markers that can contribute to the early diagnosis of high-risk patients may benefit for clinicians.[56789]

Immature granulocytes (IGs) are neutrophils from the progenitor cells in the bone marrow during maturation period and are not generally released or detected in peripheral blood in healthy individuals. However, infection can pass into peripheral blood with inflammation.[1011] Recent studies have shown that immature granulocyte count (IGC) and percentage (IG%) increase in cases of infection and sepsis.[1213] Because AP is an inflammatory disease of the pancreas that can involve surrounding tissue and distant organ systems, biomarkers have always maintained their importance, but there are very few studies in the literature showing the utility of IGC and IG%, as a new inflammatory biomarker, in predicting AP severity.[1415] Therefore, we aimed to investigate the clinical utility of IGC and IG% in predicting AP severity in our study.

Methods

This retrospective study consisted of patients admitted to our tertiary ED and diagnosed with AP between March 1 and September 30, 2019. Approximately, 360,000 patients are admitted to the ED in our hospital per year. This study was approved by the Ethics committee approval and institutional approval were received from the Clinical Research Ethics Committee of Antalya Training and Research Hospital. ?Our study was carried out by retrospectively scanning patients' data from hospital electronic information processing systems, and AP patients were investigated from the system. All information was created and saved in a template. The patients were diagnosed with AP if there were two of three findings such as typical abdominal pain at the time of admission, a threefold increase in pancreatic enzymes, and a finding in favor of AP on imaging. The diagnosis of AP was made according to clinical symptoms, laboratory results, and typical radiological findings.[14] As AP imaging findings, enlargement of the pancreas, edema, and necrosis in the necrotizing form of the disease can be seen in ultrasonography and computed tomography. Deletion of tissue plans and emergence of fluid collections can be observed in peripancreatic tissues. Patients younger than 18 years of age, pregnant patients, patients with acute exacerbations of chronic pancreatitis, patients with AP-associated malignancy, patients with hematological disorders, patients with other concomitant infections and inflammations, patients transferred to other hospitals, and patients with inadequate data were excluded from the study [Figure 1]. Demographic characteristics of the patients, disease etiology, disease severity, prognosis, length of hospital stay (LOS), Ranson scores at the time of admission, inflammation markers (white blood cell count [WBC], IGC, IG%, NLR, and CRP), and biochemical parameters were recorded.

Figure 1

Patient enrollment flow diagram

According to the determinant-based classification (DBC) system, patients were divided into two groups as mild AP (MAP) and SAP.[16] The MAP group consisted of patients without organ failure and (peri-) pancreatic necrosis. The SAP group consisted of patients with permanent or transient organ failure and/or sterile-infected (peri-) pancreatic necrosis. ?Owing to the fact that there were less than five patients in the SAP and critical AP patients in this group were included in the moderate risk group and this risk group, namely, SAP group according to DBC classification. Then, the relationship between disease severity and etiological factors, age, sex, LOS, laboratory values, and prognosis was examined. In CBC obtained from all patients at the time of admission, WBC, neutrophil, platelet, lymphocyte, IGC, IG%, CRP, and biochemistry [aspartate aminotransferase (AST), alanine transaminase (ALT), amylase, lipase, glucose, lactate dehydrogenase (LDH)] were also recorded. NLR and PLR were calculated by proportioning these parameters. Complete blood analyses were performed with Sysmex XN-1000 (Sysmex Corp., Kobe, Japan) within 1 h as routine application of our hospital by collecting blood into tubes containing potassium ethylenediaminetetraacetic acid (K-EDTA).

Statistical analysis

The statistical analysis of all variables was carried out using SPSS 18.0. Continuous variables were expressed as mean ± standard deviation; frequency and percentage (%) were used to define categorical data. Pearson's Chi-square and Fischer's exact test were used to evaluate categorical variables. In the comparison of the MAP and SAP groups in terms of parameters, Student's t-test was used for variables with normal distribution, and Mann–Whitney U test was used for variables without normal distribution. The receiver operating characteristic (ROC) analysis was performed to determine the success of inflammation markers (WBC, NLR, IGC, IG%, CRP) in showing severity in AP patients. The test with larger AUC has better diagnostic value. A value of P < 0.05 was considered statistically significant.

Results

Two hundred and twenty-seven patients who met the inclusion criteria were analyzed. One hundred and twelve patients were male (50.2%) and the mean age was 57.55 ± 19.07 years. The patients were divided into two groups as MAP and SAP according to AP severity. Of these patients, 183 (80.7%) were in the MAP group and 44 (19.3%) were in the SAP group. There was no significant difference between the MAP and SAP groups in terms of sex (P = 0.392). Although the median age was higher in the SAP group compared to the MAP group, it was not statistically significant (P = 0.183). Etiologically, AP was due to gallstones in 159 (70%), due to alcohol in 11 (4.8%), due to hyperlipidemia in 24 (10.6%), and due to other causes in 33 (14.6%) of the cases. Organ damage occurred in six patients. Four patients died in the SAP group (mortality rate 1.7%), while none of the patients died in the MAP group. According to the DBC classification, two deaths each were seen in the classification of critical and severe. When the two groups were compared in terms of LOS, the mean LOS was 4 days in the MAP group and 9 days in the SAP group, which was considered significant (P = 0.005). The mean WBC, NLR, CRP, IGC, and IG% levels were found to be significantly higher in SAP group compared to the MAP group (P < 0.05 for all markers). No significant difference was found between the groups in terms of serum amylase, lipase, AST, ALT, glucose, LDH, and mean PLR values. Demographic data, etiologic characteristics, and laboratory values of the groups were compared in Table 1.

Table 1

Demographics and laboratory findings in patients with mild and severe acute pancreatitis

	Total (n=227)	MAP (n=183)	SAP (n=44)	P
Age (years)	57.55±19.07	57.09±18.56	59.43±21.2	0.392
Gender (male); n (%)	112 (50.2)	87 (47.5)	26 (59.1)	0.183
Etiology (n, %)				0.114
Gallstone	159 (70)	134 (73.2)	25 (56.8)
Alcohol	11 (4.8)	7 (3.8)	4 (9.1)
Hyperlipidemia	24 (10.6)	19 (10.4)	5 (11.4)
Others	33 (14.6)	23 (12.6)	10 (22.7)
Laboratory tests
WBC count (×103/mm3)	12.78±5.99	11.58±4.24	17.76±8.99	<0.001
NLR	9.4±9.08	8.16±7.67	14.56±12.29	0.003
PLR	216.65±171.91	216.64±175.47	216.67±158.14	0.729
IGC (×103/mm3)	164.36±485.28	64.80±78.83	578.40±996.2	<0.001
IG%	0.84±1.47	0.47±0.22	2.4±2.86	<0.001
CRP (mg/dL)	50.72±74.22	37.2±55.72	106.9±108.62	<0.001
ALT (U/L)	157.33±182.62	163.92±192.12	132.09±135.38	0.418
AST (U/L)	194.47±215.26	200.78±224.99	170.81±169.66	0.480
Amylase (U/L)	1053.31±1116.73	1050.05±1085.75	1067.16±1253.92	0.893
Lipase (U/L)	2509.71±2425.05	2609.96±2533.32	2139.7±1873.49	0.376
Glucose (mg/dL)	149.06±72.03	148.23±74.14	152.5±63.17	0.609
LDH (U/L)	378.14±305.8	369.17±237.23	415.45±501.52	0.778
Length of hospital stay (day)	4 (1-155)	4 (1-84)	9 (1-155)	0.005
Ranson score	1 (0-4)	1 (0-4)	2 (0-4)	<0.001
Organ failure (n, %)	6 (2.6)	–	6 (13.6)	<0.001
Mortality (n, %)	4 (1.7)	–	4 (9.1)	<0.001

WBC: White blood cell; NLR: Neutrophil–lymphocyte ratio; PLR: Platelet lymphocyte ratio; IGC: Immature granulocyte count; IG%: Immature granulocyte percentage; CRP: C-reactive protein; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; LDH: Lactate dehydrogenase

In regression analysis, NLR (OR 1.057, 95% CI 1.004–1.113, P < 0.001), CRP (OR 1.011, 95% CI 1.006–1.015, P < 0.001), and IG% (OR 13.628, 95% CI 4.117–45.109, P < 0.001) have been shown to predict SAP in patients with AP [Table 2]. The utility of WBC, NLR, CRP, IGC, and IG% parameters in MAP and SAP discrimination was calculated by plotting ROC curves [Figure 2]. The utility of all these markers in predicting SAP was statistically significant (P < 0.05 for all markers). However, the power of IGC and IG% in predicting SAP was much higher than other parameters [(AUC for IGC: 0.902; sensitivity: 78.2%; specificity: 92.8%); (AUC for IG%: 0.843; sensitivity: 72.7%; specificity: 84.6%)]. The results of the ROC curve analysis are presented in Table 3.

Table 2

Predictors of severe acute pancreatitis on multivariable logistic regression analysis

			Multivariate logistic regression
Variable	Comparison	OR	95% CI	P
Age	Increase per 1 y	0.979	0.954-1.004	0.464
Sex	Male versus female	1.448	0.708-2.963	0.169
WBC (×103/mm3)	≥14.1 versus<14.1	1.096	0.982-1.223	0.082
NLR	≥6.05 versus<6.05	1.057	1.004-1.113	<0.001
IGC (×103/mm3)	≥115 versus<115	1.003	1.000-1.006	<0.001
IG%	≥0.65 versus<0.65	13.628	4.117-45.109	<0.001
CRP (mg/dL)	≥32.5 versus<32.5	1.011	1.006-1.015	<0.001
Gallstone	Yes versus no	0.326	0.131-0.813	0.016
Alcohol	Yes versus no	1.301	0.293-5.772	0.729
Hyperlipidemia	Yes versus no	0.555	0.153-2.018	0.372
Ranson score	≥2 versus<2	2.551	1.281-5.081	0.008
Organ failure	Yes versus no	1.214	0.256-5.749	0.056

OR: Odds ratio; CI: Confidence interval; WBC: White blood cell; NLR: Neutrophil–lymphocyte ratio; IGC: Immature granulocyte count; IG%: Immature granulocyte percentage; CRP: C-reactive protein

Figure 2

Receiver operating characteristic curve analysis of laboratory parameters in the discrimination between mild and severe acute pancreatitis groups

Table 3

The receiver operating characteristic curves for severe acute pancreatitis prediction

	Cutoff	AUC (95% CI)	Sensitivity (%)	Specificity (%)	P
WBC (×103/mm3)	14.10	0.737 (0.635-0.839)	70.5	76.5	<0.001
NLR	6.05	0.645 (0.544-0.747)	63.6	67.9	0.003
IGC (×103/mm3)	115	0.902 (0.852-0.951)	78.2	92.8	<0.001
IG%	0.65	0.843 (0.763-0.923)	72.7	84.6	<0.001
CRP (mg/dL)	32.5	0.745 (0.668-0.823)	61.4	71.6	<0.001

AUC: Area under the curve; CI: Confidence interval WBC: White blood cell; NLR: Neutrophil–lymphocyte ratio; IGC: Immature granulocyte count; IG%: Immature granulocyte percentage; CRP: C-reactive protein

Discussion

Early diagnosis of SAP is important because mortality rate increases in patients with SAP compared to general population with AP.[17] We found that increased WBC, NLR, CRP, IGC, and IG% were associated with AP severity in our study. However, IGC and IG% had higher predictive value in SAP detection compared to WBC, NLR, and CRP values. Therefore, we think that IGC and IG% may be an auxiliary laboratory test for early prediction of AP patients admitted to the ED.

Several scoring systems have been used to determine the clinical severity and patient prognosis in AP. The main ones are PANC3, Ranson, APACHE II, Multiple Organ System Score, and Bedside Index of Severity in Acute Pancreatitis (BISAP).[1819] The most commonly used of these scoring systems is the Ranson criteria.[4] However, new and fast scoring system and biomarker research are still ongoing. In addition, most of these scoring systems can be applied 48 h after admission, which can sometimes be too late for patients.

As is known, AP is an inflammatory process and tests for WBC count and additional serum inflammatory markers, showing inflammation is often performed in patients with suspected AP.[20] Zhou et al. reported that NLR and PLR are associated with AP sever?ity and mortality in their study.[21] Sternby et al. emphasized that CRP showed AP severity at a cutoff value of 57, with 98% sensitivity and 54% specificity in a study of 175 patients.[22] In a study, Ünal et al. reported that WBC, NLR, and CRP increase is a useful parameter in showing the severity of AP.[14] In another study by Li et al., NLR, CRP, and RDW were reported to be markers of AP severity and mortality.[23] Hu et al. stated in their study that RDW showed a positive correlation with AP severity and could be used as one of the predictors of AP severity and mortality.[24] In our study, similar to the literature, WBC, NLR, and CRP were found to be significantly higher in the SAP group compared to the MAP group, and we think that these parameters are useful parameters to show the severity of AP.

Studies have emphasized the need for an ideal biomarker that can be used in clinical practice in the early diagnosis of SAP. First of all, what is expected from this marker is quick, simple applicability, easy measurement, and cost-effectiveness. With the advances in modern technology, IGC and IG% can be obtained in minutes with automated hematology analyzers. This means that these parameters can be potential biomarkers. Recent studies have demonstrated the availability of IG% in the early and rapid diagnosis of bacterial infections and sepsis.[25] In a study conducted by Lipinski and Rydzewska in 2017, IG% was reported to be an independent predictor of AP severity with a 100% sensitivity and 96% specificity.[26] In their study of 1933 patients, Huang et al. reported that IG% >0.65 was an effective marker for Acute respiratory distress syndrome (ARDS) in AP patients with a sensitivity of 90.8% and specificity of 60.4%.[27] Unal et al. found that IG% >0.6 was an early indicator of pancreatic necrosis in AP patients with a sensitivity of 100% and specificity of 96.2% in their study.[14] In our study, we found that WBC, NLR, CRP, IGC, and IG% were inflammatory markers that could be used to determine the severity of AP; however, the power of IGC and IG% in predicting SAP was much higher than other parameters [(AUC for IGC: 0.902; sensitivity: 78.2%; specificity: 92.8%); (AUC for IG%: 0.843; sensitivity: 72.7%; specificity: 84.6%)].

Our study has some limitations. The first is that our study was retrospectively designed and performed with relatively small number of patients. Another limitation is that physical examination findings and symptoms of the patients included in our study and the time from their complaints to the collection of the samples was not recorded. In addition, the time involved in the study was short, since the IG parameter could not be measured in CBC before March 2018.

Conclusion

IGC and IG% show the severity of AP more effectively than WBC, NLR, and CRP, which are traditional inflammation markers. The values of IG% >0.65 and IGC >115 in routine CBC are early indicators of AP severity in patients diagnosed with AP.

Financial support and sponsorship

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflicts of interest

There are no conflicts of interest.