Postoperative and Long-term Survival in Relation to Life-expectancy After Pancreatic Surgery in Elderly Patients

Study design The study is a retrospective, descriptive register study based on data from a prospectively maintained database. Data recruitment include all patients from the age of 18 with adenocarcinoma in the pancreas, papilla of vater and duodenum operated between January 1, 2010 and December 31, 2019 with a minimum of one year post-operative follow-up. Study completion date will be December 31, 2020. Patients are divided into two cohorts, patients younger than 75 years and patients 75 years and older. Moreover, data are divided into patients with malignant and non-malignant tumors. The study is reported according to the STROCSS guidelines (www.strocssguideline.com).

Study population The study includes 1,556 consecutive patients, 1,296 patients between 18 and 75 years and 260 patients aged 75 years and older. There are 1,208 patients with malignant tumours of whom 1,020 have adenocarcinoma. The remaining 348 patients have benign or no pathologic findings but were operated for pre-malignant diseases or on suspicion of a malignant tumor.

Data collection Data are collected from our prospectively maintained database of pancreatic operations, from the electronic hospital record systems Orbit and EPIC, the Danish National Pathology Data Registry, and from the National Register of Death. All Danish Nationals have a unique Central Person Registration number that enables searching of health data. Patients from the Faroe Islands and Greenland are excluded, as they are not recorded in the Danish death register.

Outcomes Relevant postoperative complications are recorded in the study and include leakage from the pancreatic, bile or gastrojejunal anastomosis, intraabdominal hemorrhage and abscess formation or other complications with severe or fatal outcome. Outcomes are defined as postoperative complications and mortality assessed during 30- and 90-days and overall survival (OS) defined as the time from surgery to death from any cause or censoring at time of last follow-up. Hospitalization is defined as postoperative stay until discharge. In-hospital mortality is defined as all deaths from time of admission until discharge. Cancer specific mortality is defined as death from adenocarcinoma after other causes are censured. Recorded years of life lost are defined as lost years compared to the expected remnant life of an age-matched standard population. The recorded years of life lost are the number of deprived years that could have been saved, if patient had not developed an event that had shortened life.

Statistics Data are presented as median and range if not otherwise stated. Categorial data are presented as numbers or percentage and are analyzed with Fisher's exact test. Non-parametric continuous data between subgroups are analyzed with the Mann-Whitney test. The Kaplan-Meier method and the cumulative incidence function with correction for competing risks are used to estimate OS and the log-rank test to examine the differences between curves. The expected years of life lost are calculated as the difference between the area under the survival curve of the reference population and the patient population. The reference population is an age and sex matched Danish standard population. A p < 0.05 is considered statistically significant. Statistical analysis is performed with GraphPad Prism software version 6.05. (GraphPad, La Jolla, CA).