Seasonal variations in pancreatic surgery outcome A retrospective time-trend analysis of 2748 Whipple procedures

BACKGROUND: Observing cyclic patterns in surgical outcome is a common experience. We aimed to measure this phenomenon and to hypothesize possible causes using the experience of a high-volume pancreatic surgery department. METHODS: Outcomes of 2748 patients who underwent a Whipple procedure at a single high-volume center from January 2000 to December 2018 were retrospectively analyzed. Three different hypotheses were tested: the effect of climate changes, the “July effect” and the effect of vacations. RESULTS: Clavien-Dindo ≥ 3 morbidity was similar during warm vs. cold months (22.5% vs. 19.8%, p = 0.104) and at the beginning of activity of new trainees vs. the rest of the year (23.5 vs. 22.5%, p = 0.757). Patients operated when a high percentage of staff is on vacation showed an increased Clavien-Dindo ≥ 3 morbidity (22.3 vs. 18.5%, p = 0.022), but similar mortality (2.3 vs. 1.8%, p = 0.553). The surgical waiting list was also significantly longer during these periods (37 vs. 27 days, p = 0.037). Being operated in such a period of the year was an independent predictor of severe morbidity (OR 1.271, CI 95% 1.086–1.638, p = 0.031). CONCLUSION: Being operated when more staff is on vacation significantly affects severe morbidity rate. Future healthcare system policies should prevent the relative shortage of resources during these periods.