Risk factors for morbidity after appendectomy

The aim of the present study was to evaluate the risk factors for postoperative complications after an appendectomy with special regard to both the time period from hospital admission to operation and night time surgery.

Patients who underwent an appendectomy due to acute appendicitis and were admitted to the University Hospital Aachen between January 2003 and January 2014 were included in this retrospective analysis. Regarding the occurrence of postoperative complications, patients were divided into the following two groups: the group with complications (group 1) and the group without complications (group 2).

Of the 2136 patients who were included in this study, 165 patients (group 1) exhibited complications, and in 1971 patients (group 2), no complications appeared. After a univariate logistic regression analysis, six predictors for postoperative complications were found and are described as follows: (1) complicated appendicitis (odds ratio (OR) 4.8 (3.46-6.66), p < 0.001), (2) operation at night (OR 1.62 (1.17-2.24), p = 0.004), (3) conversion from laparoscopic to open access (OR 37.08 (12.95-106.17), p < 0.001), (4) an age > 70 years (OR 6.00 (3.64-9.89), p < 0.001), (5) elevated CRP (OR 1.01 (1.01-1.01), p < 0.001) and (6) increased WBC count (OR 1.04 (1.01-1.07), p = 0.003). After multivariate logistic regression analysis, a significant association was demonstrated for complicated appendicitis (1.88 (1.06-3.32), p < 0.031), conversion to open access (OR 16.33 (4.52-58.98), p < 0.001), elevated CRP (OR 1.00 (1.00-1.01), p = 0.017) and an age > 70 years (OR 3.91 (2.12-7.21), p < 0.001). The time interval between hospital admission and operation was not associated with postoperative complications in the univariate and multivariate logistic regression analyses, respectively. However, the interaction between complicated appendicitis and the time interval to operation was significant (OR 1.024 (1.00-1.05), p = 0.028).

Based on our findings, surgical delay in the case of appendicitis and operation at night did not increase the risk for postoperative complications. However, the mean waiting time was less than 12 h and patients aged 70 years or older were at a higher risk for postoperative complications. Furthermore, for the subgroup of patients with complicated appendicitis, the time interval to surgery had a significant influence on the occurrence of postoperative complications. Therefore, the contemporary operation depending on the clinical symptoms and patient age remains our recommendation.