Does modified computed tomography severity index need a revision?

Suhail Rafiq; Obaid Ashraf; Inayat Elahi; Navneet Kaur; Musaib Ahmad Dar

doi:10.4103/jcrsm.jcrsm_23_20

ORIGINAL ARTICLE

Year : 2020 | Volume : 6 | Issue : 2 | Page : 89-95

Does modified computed tomography severity index need a revision?

Suhail Rafiq, Obaid Ashraf, Inayat Elahi, Navneet Kaur, Musaib Ahmad Dar
Department of Radiodiagnosis, Government Medical College, Srinagar, Jammu and Kashmir, India

Date of Submission	08-Apr-2020
Date of Decision	27-Apr-2020
Date of Acceptance	08-May-2020
Date of Web Publication	21-Dec-2020

Correspondence Address:
Musaib Ahmad Dar
Resident Hostel, Government Medical College, Srinagar - 190 010, Jammu and Kashmir
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jcrsm.jcrsm_23_20

Abstract

Background: Several radiologic prognostic scoring systems have been developed in the past for grading of pancreatitis. Modified computed tomography severity index (MCTSI) incorporates extrapancreatic complications in the assessment and simplifies the evaluation of the extent of pancreatic parenchymal necrosis and peripancreatic inflammation. MCTSI does not give detailed evaluation with regard to the specific prevalence of each of the extrapancreatic complications. All extrapancreatic complications are given a score of 2.
Objective: The primary aim of our study is whether vascular extrapancreatic complication has an overall effect on clinical outcome in pancreatitis.
Materials and Methods: This was a hospital-based prospective correlational study done in Government Medical College, Srinagar, from December 2018 to November 2019, on patients with acute pancreatitis. Twenty-seven patients of acute severe pancreatitis, as per MCTSI, were divided into the following two groups: Group A of 18 patients having no vascular complications and Group B of nine patients with vascular complications, and 28 patients of moderate pancreatitis were divided into the following two groups: Group A of 24 patients with no extrapancreatic vascular complications and Group B of four patients having vascular complications. Major parameters that were evaluated were rate of intervention, infection rate, organ involvement, and duration of hospital stay in patients with vascular complications as compared to patients having no vascular complications.
Results: Pleural effusion was the most common extrapancreatic complication in our study followed by ascites. Thrombosis was the most common vascular complication followed by pseudo aneurysm. Cholelithiasis was the most common cause of acute pancreatitis followed by idiopathic cause. Patients with vascular complications had higher intervention, infection rate, organ involvement, and longer duration of hospital stay.
Conclusion: Patients with vascular complications have higher rate of intervention, infection rate, organ involvement, and longer duration of hospital stay irrespective of MCTSI.

Keywords: Necrosis, pancreatitis, thrombosis

How to cite this article:
Rafiq S, Ashraf O, Elahi I, Kaur N, Dar MA. Does modified computed tomography severity index need a revision?. J Curr Res Sci Med 2020;6:89-95

How to cite this URL:
Rafiq S, Ashraf O, Elahi I, Kaur N, Dar MA. Does modified computed tomography severity index need a revision?. J Curr Res Sci Med [serial online] 2020 [cited 2023 May 30];6:89-95. Available from: https://www.jcrsmed.org/text.asp?2020/6/2/89/304200

Introduction

Acute pancreatitis is the inflammation of the pancreas that occurs due to exudation of pancreatic fluid containing proteolytic enzymes into the pancreatic interstitium and into the surrounding tissues. Acute pancreatitis is broadly classified into two subtypes: interstitial edematous pancreatitis (IOP) and necrotizing pancreatitis. Majority of patients have mild IOP which is self-limiting. However, approximately 15%–20% of patients develop clinically severe AP with local and systemic complications.^[1] Patients with severe pancreatitis can progress to a systemic inflammatory response syndrome with significant morbidity and mortality.^[2] A number of clinical and laboratory prognostic scoring systems have been designed for the early identification of patients at greatest risk of developing clinically severe AP. Overall, these scoring systems have an accuracy varying between 70% and 80%.^[3]

Choledocholithiasis and alcoholism are the leading causes of acute pancreatitis. Other causes include trauma, metabolic disorders (hyperlipidemia, hypercalcemia), endoscopic retrograde cholangiopancreatography-induced pancreatitis, medications (azathioprine, sulphonamides), tumors, and idiopathic and congenital anomalies such as pancreas divisum.^[4]

Pancreas is a retroperitoneal organ surrounded by fat. Portospleenic confluence lies posterior to the neck of pancreas. It is closely related to superior mesenteric artery and lies within the C-loop formed by duodenum.^[5] It has homogenous computed tomography (CT) attenuation and on postcontrast images, the mean attenuation of pancreas is 50–80 Hounsfield Units.^[6],[7] The gold standard imaging modality in acute pancreatitis is contrast-enhanced CT (CECT).^[8] The ideal time for CECT in acute pancreatitis is 48–72 h as it increases the chances of picking necrotizing pancreatitis.^[9]

Several radiologic prognostic scoring systems have been developed in the past. In 1990, Balthazar introduced CT severity index (CTSI) as a grading system for assessing the severity of acute pancreatitis.^[6] However, this scoring system did not include extrapancreatic complications such as organ failure and vascular complications.^[6],[10] In 2004, a Modified Computed Tomography Severity Index (MCTSI) was designed to account for several potential limitations of the CTSI.^[11] In contrast to the CTSI, the MCTSI incorporates extrapancreatic complications in the assessment and simplifies the evaluation of the extent of pancreatic parenchymal necrosis (none, ≤30%, or >30%) and peripancreatic inflammation (presence or absence of peripancreatic fluid). In the initial study of the MCTSI, no detailed evaluation was provided with regard to the specific prevalence of each of the extrapancreatic complications. All extrapancreatic complications are given a score of 2. The primary aim of our study whether vascular extrapancreatic complication has an overall effect on clinical outcome. Is there a need for giving a separate score to vascular extrapancreatic complications?

Materials and Methods

This was a hospital-based prospective correlational study done in the Postgraduate Department of Radiodiagnosis and Imaging, Government Medical College, Srinagar, for a period of 1 year from December 2018 to November 2019, on patients with clinical/laboratory/ultrasonography findings suggestive of acute pancreatitis. CECT was done on 256-slice Siemens Somatom Skyra (Siemens Healthineers India) with 120 kVp and 300 mAs. Noncontrast and postcontrast images of chest, abdomen, and pelvis were taken using intravenous nonionic Omnipaque at a dose of 1.5–2 ml/kg dose at rate of 3–4 ml/s. Different phase such as arterial, portal, and venous phases were taken to rule out any vascular complication. The modified CTSI was calculated [Table 1] and categorized as:

Table 1: Mortele Modified Computed Tomography Severity Index scoring (2004)

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Mild pancreatitis modified CTSI score 0–2
Moderate pancreatitis modified CTSI score 4–6
Severe pancreatitis modified CTSI score 8–10.

As vascular complications were seen in patients of moderate and severe pancreatitis, patients with mild pancreatitis were not included in our study. Twenty-seven patients of acute severe pancreatitis were divided into the following two groups: Group A of 18 patients having no vascular complications and Group B of nine patients with vascular complications, and 28 patients of moderate pancreatitis were divided into the following two groups: Group A of 24 patients with no extrapancreatic vascular complications and Group B of four patients with vascular complications.

Clinical parameters that were assessed and collected from different departments include days of hospital stay; need for vascular, nonvascular or surgical intervention; evidence of any sign of infection (fever >100°F and white blood count >12,000/mm≥); evidence of organ failure (PaO₂<60 mmHg or need of ventilation, diastolic blood pressure [BP] <60 mmHg or systolic BP of <90 mmHg or urine output of <500 ml/24 h); and death.

Diagnostic criteria for pancreatitis

Acute abdominal pain and tenderness suggestive of pancreatitis
Serum amylase/lipase ≥3 times the normal
Imaging findings (ultrasound and/or CT) suggestive of acute pancreatitis.

Exclusion criteria

Mild acute pancreatitis as per MCTSI
Patients with known history of allergy to iodinated contrast agents
Patients with serum creatinine >1.5 mg/dl
Pregnant patients
Patients with chronic pancreatitis or other pancreatic pathology such as neoplasm and cysts.

Statistical analysis

The study data from both patient groups (with and without vascular complications) were entered in an Excel spreadsheet. The data were cross-tabulated, and data analysis was done using SPSS software version 16.0 (SPSS South Asia (P) Ltd, Bangalore, India). The measures of central tendency for continuous variables were summarized as mean and standard deviations. Data were represented as frequency and percentages. Chi–square test was applied for ordinal variables, and P value was calculated. P < 0.05 was considered statistically significant.

Results

Out of 27 patients of severe pancreatitis, 15(55.5%) were males and 12 (44.4%) were females. Out of 28 patients of moderate pancreatitis, 16(57.2%) were males and 12(42.8%) were females. Age limit of patients in our study was 22-76 years with maximum patients in 40-50 age group with mean age of 44.3 years. Cholelithiasis was the most common cause of acute pancreatitis accounting for 65% cases followed by idiopathic cause in 21.8% cases [Table 1]. In our study, average length of hospital stay in group A and group B of severe pancreatitis was 20.6 and 23.6 days. On average the duration of hospital stay was 1.13 times greater in group B. Rate of intervention in group A and group B of severe pancreatitis was 33.3% (6 out 18) and 66.6% (6 out of 9) with an observed p-value of 0.066 and likelihood ratio of 0.048 [Diagram 1]. Infection was seen in 4 (22.2%) of group A and 3(33.3%) of group B patients of severe pancreatitis. Group B patients were 1.85 times more likely to develop infection as compared to group A patients. (P= 0.653). Organ failure was seen in 3(16.6%) patients of group A and 2(22.2%) of group B of severe pancreatitis. The likelihood of organ failure was 1.36 times more in patients belonging to group B (P= 0.553). Death was seen in 1(5.5%) of group A and 1(11.1%) patients of group B.

Average length of hospital stay in group A and group B of moderate pancreatitis was 10.8 and 12.75 days, with group B having a 1.18 times higher average duration of hospital stay. Rate of intervention in group A and group B of moderate pancreatitis was 25% (6 out of 24) and 75% (3 out of 4) with a statistically significant p-value of 0.04 [Diagram 2]. Infection was seen in 4 patients (16.7%) of group A and 1 patient (25%) of group B of moderate pancreatitis, with group B patients being 1.43 times more likely to develop pancreatitis (P = 0.687). No case of organ failure was seen in patients of moderate pancreatitis. No death was seen in patients of moderate pancreatitis [Table 2]. Pleural effusion was the most common extra pancreatic complication with right sided effusion being more common than bilateral effusion. 66.6% patients of group A and group B with severe pancreatitis had pleural effusion (P > 0.999). 66.7% of group A and 75% with group B with moderate pancreatitis had pleural effusion( group B patients were 1.36 times more likely to develop pleural effusion with p =0.741) Ascites was seen in 61.1% patients of group A and 66.6% patients of group B with severe pancreatitis (group B being 1.29 times more likely to develop ascites with P= 0.778). 62.5 % patients of group A and 75% patients of group B with moderate pancreatitis had ascites (likelihood of developing ascites being 1.61 times greater in group B with P = 0.629). 22.2% patients of both group A and group B with severe pancreatitis had gastrointestinal involvement in form of inflammatory thickening (equal likelihood of gastrointestinal involvement in both groups with P > 0.999). 16.6% and 25% patients with moderate pancreatitis had gastrointestinal involvement in form of inflammatory thickening (the likelihood of gastrointestinal involvement was 1.43 times more in group B patients with P=0.687). Organ involvement was seen in 11.1% (2) and 11.1% (1) cases of group A and group B respectively in severe pancreatitis in form of subcapsular collection (equal likelihood of organ involvement in both groups with P > 0.999) [Table 3] and [Table 4].

Table 2: Causes of acute pancreatitis

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Table 3: Depiction of extrapancreatic complications in severe pancreatitis

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Table 4: Comparison of clinical parameters in Group A and Group B of severe pancreatitis

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The common causes of Acute pancreatitis in our study were as depicted in [Table 2].

Severe pancreatitis cases [Table 3] and [Tables 4]

Moderate pancreatitis cases

Thrombosis was the most common vascular complication seen in seven cases of severe pancreatitis and three cases of moderate pancreatitis. Five patients had thrombosis of portal vein, three had splenic vein thrombosis, and one patient had thrombus involving inferior vena cava and superior mesenteric vein. Pseudoaneurysm was seen in three cases with two in severe pancreatitis and one in moderate pancreatitis. Two patients had pseudoaneurysm of splenic artery and one patient had gastroduodenal artery pseudoaneurysm [Table 3] and [Table 5].

Table 5: Depiction of extrapancreatic complications in moderate pancreatitis

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Discussion

The age limit of patients in our study was 22–76 years, with maximum patients in 40–50 age group with a mean age of 44.3 years. Seventeen out of 27 patients of severe pancreatitis were males and 10 out of 27 were females, with a male-to-female ratio of 1.7. Seventeen out of 28 patients of moderate pancreatitis were males and 11 out of 28 patients were females, with a male-to-female ratio of 1.54. The total male-to-female ratio was 1.6. A prospective study done by Silverstein et al. also showed a male preponderance with a male: female ratio of 2:1.^[12] The male-to-female ratio in the study done by Gonapati et al.^[13] was 1.6 similar to our study. Cholelithiasis (65.4%) was the most common cause followed by idiopathic cause (21.8%). A prospective study done by Raghuwanshi et al.^[14] on fifty patients also found that cholelithiasis (42%) and alcoholism (38%) were the major causes of acute pancreatitis. Gonapati et al.^[13] found the most common etiology to be cholelithiasis (43.75%) followed by alcoholism (37.5%), idiopathic (12.5%), hypertriglyceridemia (4.17%), and drug-induced (2.08%). Our study was done in Kashmir which is a Muslim majority state and alcoholism is prohibited in Islam, hence alcoholism was the less common cause of pancreatitis in our study.

Complications

Pleural effusion was the most common extrapancreatic complication in our study, with right-sided effusion being more common than bilateral effusion. Ascites was the second most common extrapancreatic complication followed by gastrointestinal (GI) thickening in our study. Gonapati et al.^[13] in their study found that 33 patients (68.75%) had pleural effusion followed by ascites (33.33%). Right-sided pleural effusion was more common than bilateral effusion in their study, similar to our study. A study done by Banday et al.^[15] on fifty patients stated that ascites (36%) was the second most common extrapancreatic complication followed by GI involvement (26%).

Presence of extrapancreatic nonvascular complications such as pleural effusion, ascites, GI involvement, and other organ involvement is independent of the presence of vascular complications, as demonstrated in [Table 3] and [Table 5], in both severe and moderate pancreatitis. None of the nonvascular complication was statistically significant in Group A as compared to Group B.

Thrombosis was seen in ten patients [Figure 1] and [Figure 2]: seven in severe pancreatitis and three cases in moderate pancreatitis. Pseudoaneurysm was found in three cases: two in severe pancreatitis and one in moderate pancreatitis. Banday et al.^[15] in their study found that venous thrombosis was the most common (three in portal vein and one in splenic vein) followed by two cases of pseudoaneurysm, both in splenic artery [Figure 3], [Figure 4], [Figure 5].

Figure 1: Axial contrast-enhanced computed tomography revealing evidence of thrombus in splenic vein with pigtail within peripancreatic collection

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Figure 2: Axial contrast.enhanced computed tomography revealing evidence of thrombus in splenic vein with >30% necrosis and acute necrotic collection

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Figure 3: Axial contrast-enhanced computed tomography revealing evidence of multiple subcapsular hepatic collections with peripancreatic fluid

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Figure 4: Axial arterial revealing small outpouching from splenic artery suggestive of pseudoaneurysm in a patient with acute pancreatitis

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Figure 5: Axial arterial and portal phase revealing partially thrombosed splenic artery pseudoaneurysm secondary to pancreatitis

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Clinical parameters/outcome

Various clinical parameters/outcome that were evaluated in our study include days of hospital stay; need for vascular, nonvascular or surgical intervention; evidence of any sign of infection (fever >100°F and white blood count >12,000/mm≥); evidence of organ failure (PaO₂<60 mmHg or need of ventilation, diastolic BP <60 mmHg or systolic BP of <90 mmHg or urine output of <500 ml/24 h); and death.

Days of hospital stay

In our study, the average length of hospital stay in Group A and Group B of severe pancreatitis was 20.6 and 23.6 days, whereas in cases of moderate pancreatitis, it was 10.8 and 12.75 days, respectively [Table 4] and [Table 6]. On an average, the duration of hospital stay was 1.13 times greater in Group B in severe pancreatitis, whereas in cases of moderate pancreatitis, it was 1.18. Though hospital stay was prolonged in cases with vascular complications, it was not statistically significant (P > 0.05).

Table 6: Comparison of clinical parameters in Group A and Group B of moderate pancreatitis

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Rate of intervention

The rate of intervention in Group A and Group B of severe pancreatitis was 33.3% (6 out 18) and 66.6% (6 out of 9), with an observed P = 0.066 and a likelihood ratio of 0.048 [Diagram 1], whereas in moderate pancreatitis, it was 25% (6 out of 24) and 75% (3 out of 4), respectively, with a statistically significant P = 0.04 [Diagram 2]. It depicts that patients of moderate pancreatitis with vascular complications have statistically significant intervention rates in comparison to patients without vascular complications [Table 4] and [Table 6]. Though data are sparse, we can conclude that intervention rates are more in vascularly complicated pancreatitis irrespective of the severity of pancreatitis.

Infection and organ failure

Infection was seen in four (22.2%) of Group A and three (33.3%) of Group B patients of severe pancreatitis. Group B patients were 1.85 times more likely to develop infection as compared to Group A patients (P = 0.653), whereas in moderate pancreatitis, Group B patients were 1.43 times more likely to develop infections (P = 0.687). Though infection rate is more in patients with vascular complications, it is not statistically significant, reason again being a smaller number of patients in the study.

Organ failure was seen in three (16.6%) patients of Group A and two (22.2%) of Group B of severe pancreatitis. The likelihood of organ failure was 1.36 times more in patients belonging to Group B (P = 0.553). Death was seen in one (5.5%) of Group A and one (11.1%) patients of Group B in severe pancreatitis. No case of organ failure was seen in patients of moderate pancreatitis. No death was seen in patients of moderate pancreatitis.

The average length of hospital stay, rate of intervention, infection rate, organ involvement, and death percentage were more common in Group B of severe pancreatitis as compared to Group A of severe pancreatitis. The average length of hospital stay, rate of intervention, and infection rate were more common in Group B of moderate pancreatitis as compared to Group A of moderate pancreatitis. Our study is the first of its kind to compare patients with and without vascular complications in severe and moderate pancreatitis. These may be attributed to more severe form of inflammation in patients with vascular complications. Second, patients with vascular complications are often treated with vascular intervention, which increases the chances of infection and length of hospital stay. The major limitation of our study was the small size of population with vascular complications.

Conclusion

According to our study, patients with vascular complications have higher rate of intervention, infection rate, organ involvement, and longer duration of hospital stay irrespective of modified CTSI, but significant statistical correlation was not observed except for rate on intervention in moderate pancreatitis. Hence, further studies with bigger samples of population are needed to confirm whether vascular complications can be given more weightage in MCTSI or not.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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