Short-term outcome after appendectomy is related to preoperative delay but not to the time of day of the procedure: A nationwide retrospective cohort study of 9224 patients

Introduction: Acute appendicitis is among the most common indications for emergency abdominal surgery. The risk of perforation might increase with a delay in treatment. Therefore, appendicitis is considered a surgical emergency, leading to appendectomies being frequently performed off-hours. However, numerous studies from other medical specialties have shown less favourable outcomes in patients admitted or treated off-hours than in those treated during regular working hours. The purpose of this study was to determine whether the time of day of the procedure and preoperative delay in appendectomy have significant impacts on morbidity and mortality rates.

Methods: All appendectomies recorded in a prospective national quality measurement database (Arbeitsgemeinschaft für Qualitätssicherung in der Chirurgie (AQC)) between 2010 and 2017 were retrospectively analysed. The inclusion criteria were appendicitis (International Classification of Diseases diagnostic codes K35-K37), surgical treatment (appendectomy), and available information on the time of day the appendectomy was performed. We stratified patients into four groups according to the start of the operation-'MORNING' for surgeries started between 7:00 a.m. and 12:59 p.m., 'AFTERNOON' for surgeries started between 1:00 p.m. and 6:59 p.m., 'EVENING' for surgeries started between 7:00 p.m. and 11:59 p.m., and 'NIGHT' for surgeries started between midnight and 6:59 a.m. In a further analysis, we examined differences between patients who underwent surgery on the admission day and those who underwent surgery later. A total of 9224 patients with a mean age of 36 ± 19 years (54% men) were included and further analysed. The occurrence of any complication was the primary outcome, whereas in-hospital mortality was the secondary outcome. Variables were entered into bivariate and multivariate analyses.

Results: Of the appendectomies, 38% were performed during the afternoon, 31% in the evening, 18% in the morning, and 13% at night-time. Patients who underwent surgery at night had slightly lower American Society of Anesthesiologists scores, were more often managed as emergency cases (98% of the cases), had fewer comorbidities, and were more often covered by statutory instead of private health insurance than the other patients. Junior attending and resident surgeons performed 88% of all night-time operations. The average duration of surgery was not significantly longer in the night-time group than in the day-time groups. The overall complication rate was 4.7%, ranging from 3.5% in the 'NIGHT' group to 5.0% in the 'AFTERNOON' group. However, the differences between the groups were not significant. The in-hospital mortality rate was 0.12% (n = 11), ranging from 0.082% (n = 1) in the 'NIGHT' group to 0.17% (n = 5) in the 'EVENING' group. The timing of appendectomy was not associated with mortality. However, the rates of complications, in-hospital mortality, and conversion were all significantly higher in patients with a preoperative delay of >24 h.

Conclusions: The time of day of performing an appendectomy does not seem have any significant effect on complication and mortality rates. However, a longer length of preoperative stay significantly increases the risk of complications and mortality. Night-time operations should be preferred over next-day surgery considering the equal perioperative risks observed in this study.