title: Clinical outcomes of combined necrotizing pancreatitis versus extrapancreatic necrosis alone.
abstract: BACKGROUND
  Extrapancreatic necrosis (EPN) alone, i.e., in the absence of pancreatic parenchyma necrosis has gradually come to be regarded as a separate entity of acute necrotizing pancreatitis (ANP). However, data regarding the prognostic significance of EPN are quite limited, and the outcomes of interventions for patients with EPN alone are not well elucidated. The aim of this study was to explore the differences in the outcomes of patients with EPN alone and patients with both the pancreatic parenchyma and extrapancreatic necrosis (combined necrosis).
  
  
  METHODS
  From January 2009 to December 2013, a total of 334 patients with ANP who had received interventions in the West China Hospital in China were included. Based on the extent of necrosis as assessed with contrast-enhanced CT, the patients were divided into Group 1 (n = 285) in which the necrosis involved both the pancreatic parenchyma and extrapancreatic tissues (combined necrosis) and Group 2 (n = 49) in which the necrosis involved only the extrapancreatic tissues. Additionally, Group 3 included 443 patients with interstitial pancreatitis who were also included in the analyses. The demographic characteristics, support treatment information, organ failure information, infection necrosis, persistent systemic inflammatory response syndrome (SIRS) in the first week of onset, CT severity index, and intervention types, as well as the postoperative stay lengths, ICU utility, and complications were collected and compared.
  
  
  RESULTS
  Compared with the patients in Group 1, the patients in Group 2 suffered less persistent SIRS in the first week of onset (12/24.5% vs. 145/50.9%; P < 0.05), less persistent organ failure (6/12.2% vs. 95/33.3%; P < 0.05), less persistent multiple organ failure (3/6.1% vs. 67/23.5%; P < 0.05), and less bacteremia (5/10.2% vs. 107/37.5%; P < 0.001). The intervention types were significantly different between the two groups (P < 0.001); initial open necrosectomy was performed in 174/61.6% and 8/16.3% of the patients in Groups 1 and 2, respectively, and initial percutaneous catheter drainage (PCD) was performed in 73/25.6% and 29/59.2% of the patients in the two respective groups. Second open necrosectomies following PCD were required in 61/83.5% and 9/31.0% of the patients in Groups 1 and 2, respectively (P < 0.001). A greater number of patients in Group 1 were diagnosed with infected necrosis (204/71.6% vs. 10/20.4%; P < 0.001) and had to be sent to the ICU for further postoperative care (221/77.5% vs. 23/46.9%; P < 0.001). The postoperative stay was longer for Group 1 (median: 43.0 vs. 26.5 days; P < 0.001). Residual necrotic tissue or abscess was the most common postoperative complication in both groups. The mortality was higher in Group 1 (52/18.2% vs. 1/2.1%; P < 0.05). Compared with the patients in Group 2, the patients with interstitial pancreatitis exhibited milder courses and better outcomes. Subgroup comparisons with Group 1 indicated that early multiple organ failure was significantly associated with higher mortality.
  
  
  CONCLUSIONS
  The patients with EPN alone exhibited significantly better prognoses than those with combined necrosis, and EPN alone should be regarded as a separate group of acute necrotizing pancreatitis. Open necrosectomy can be avoided in the majority of patients with EPN alone, who receive PCD as the initial first intervention.
authors.affiliation: Department of Pancreatic Surgery, West China Hospital, Sichuan University, No. 37, Guoxue Alley, Chengdu, Sichuan province, 610041, China.
authors.forename: Mingjun
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Pancreatic Surgery, West China Hospital, Sichuan University, No. 37, Guoxue Alley, Chengdu, Sichuan province, 610041, China.
authors.forename: Ailin
authors.initials: A
authors.lastname: Wei
authors.affiliation: Department of Pancreatic Surgery, West China Hospital, Sichuan University, No. 37, Guoxue Alley, Chengdu, Sichuan province, 610041, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Department of Pancreatic Surgery, West China Hospital, Sichuan University, No. 37, Guoxue Alley, Chengdu, Sichuan province, 610041, China.
authors.forename: Zhaoda
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Pancreatic Surgery, West China Hospital, Sichuan University, No. 37, Guoxue Alley, Chengdu, Sichuan province, 610041, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Lu
authors.affiliation: Department of Pancreatic Surgery, West China Hospital, Sichuan University, No. 37, Guoxue Alley, Chengdu, Sichuan province, 610041, China.
authors.forename: Ang
authors.initials: A
authors.lastname: Li
authors.affiliation: Department of Pancreatic Surgery, West China Hospital, Sichuan University, No. 37, Guoxue Alley, Chengdu, Sichuan province, 610041, China. Electronic address: weiminghu1964@126.com.
authors.forename: Weiming
authors.initials: W
authors.lastname: Hu
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D010179:Pancreas / Q000473:pathology*; D019283:Pancreatitis, Acute Necrotizing / Q000473:pathology*
keywords: Acute necrotizing pancreatitis; Complications; Extrapancreatic necrosis; Multiple organ failure; Pancreatic parenchyma necrosis; Prognosis