Textbook Outcome in Distal Pancreatectomy

Retrospective, multicenter, observational study of prospectively recorded data regarding DP carried out at 8 hepato-pancreato-biliary (HPB) surgical units between 1 January 2008 and 31 December 2018. Five are high-volume HPB units at level 3 hospitals in Spain, the highest level in our country; one is the reference center for HPB surgery and transplantation in Puerto Rico, and two are level 2 hospitals in Spain. Six authors are UEMS HPB Board Certificate.

Each participating center appointed a local manager to carry out the data collection and to liaise with the overall study coordinator. All the data were collected by the local managers at each hospital, and the project coordinator had access to medical data only.

The study has been conducted in accordance with the Declaration of Helsinki (2013), and was approved by the institutional ethics committee of the Hospital Universitario de Guadalajara (CEIm: 2018.17.EO) (27-11-2018). The need to obtain patients' informed consent was waived since the study was retrospective and observational, and entailed no risk.

Inclusion criteria were any scheduled PD performed for any diagnosis and age >18 years. Exclusion criteria were PD with celiac trunk resection. The suspected preoperative diagnosis was based on CT, MRI and EUS plus biopsy. The surgical approach was either open or laparoscopic, with or without spleen preservation. Complications were assessed at 90 days using the Clavien-Dindo (CD) classification, and those defined as Clavien-Dindo grade III or IV were considered major; they were recorded from the electronic medical and nursing notes or clinical histories of each patient. For complications specific to pancreatic surgery, the definitions of the International Study Group on Pancreatic Surgery (ISGPS) for delayed gastric emptying, post-pancreatic hemorrhage and pancreatic fistula were used. The resection margins of the specimen were categorized according to the Royal College of Pathologists definitions: R0 (margin to the tumor ≥ 1mm), R1 (margin to the tumor < 1mm) and R2 (macroscopically positive margin). Invasive tumors were staged according to the TNM classification (8th ed.). The follow-up scheme applied at all centers comprised 3 or 6-month outpatient clinic visits during the first five years depending on diagnosis, including tumor marker assessment and CT/MRI, and after five years an annual visit (in non-invasive cases). TO-DP was defined including classical variables: hospital stay p < 75, Clavien-Dindo complication Grade ≥ 3, in-hospital mortality and re-admission within 90 days, and pancreatic fistula (grade B or C).

Variables

The following variables were included in the study. Epidemiological variables: age, sex, past abdominal surgeries, medication and ASA; Clinical variables: symptoms, serological tests, leukocytes, hemoglobin (gr/dl); Radiological/diagnostic variables: vascular infiltration (arterial and venous) and preoperative biopsy; Surgical variables: type of approach (open/laparoscopy), spleen preservation, associated organ resection, intraoperative red blood cell (p-RBC) transfusion; Postoperative course: morbidity and mortality (according to the CD classification), pancreatic fistula, postoperative hemorrhage and delayed gastric emptying (if present, classified according to the ISGPS classification), hospital stay and readmissions. The histological data recorded were tumor size and size of resected pancreas.

Statistical analysis

Descriptive statistics were calculated using frequencies and percentages for categorical data, and medians and interquartile ranges (IQR) for continuous data. Differences between groups in the case of quantitative variables were analyzed using the non-parametric Mann-Whitney U test, and differences between percentages or frequencies using Pearson's Chi-square test. A p value < 0.05 was considered statistically significant. Logistical regression analyses were performed to investigate possible relationships between the characteristics of the variables and the achievement of TO. First, univariate analysis was used to explore the unadjusted association between each variable and outcome. Then, variables with a p value < 0.10 were included in the multivariate analysis. Calculations were performed using the programs Microsoft Excel for Mac, version 16.49 and SPSS for Mac, version 26.0 (SPSS Inc., Chicago, Illinois, USA).