Up till now initiated research projects worldwide mainly focus on simple appendicitis (questioning the necessity of an appendectomy). However, complex appendicitis is associated with significant morbidity (up to 30%), prolonged hospital stay and high costs. Identification of the optimal treatment strategy for children with complex appendicitis is therefore essential. Heterogeneity in the treatment of complex appendicitis still exists in daily practice and reflects the lack of high-quality data and emphasizes the need for well-designed studies. Complex appendicitis can be divided into two subtypes:~Complex appendicitis without mass/abscess. (subgroup 1) Although (inter)national guidelines agree that appendectomy should be usual care, the optimal approach (open or laparoscopy) is unclear. Laparoscopic appendectomy (LA) is increasingly applied both in adults (80%) and children (60%). Benefits reported for LA in children are, but not limited to, less superficial site infection (SSI), reduced length of hospital stay and significant less postoperative bowel obstruction compared with open appendectomy (OA). Reluctance for usage of LA in this specific subgroup, however, remains due to the potential higher incidence of post-appendectomy abscess formation (PAA) reported. However, the quality of studies on this topic is low and there is considerable inconsistency in results.~Complex appendicitis with mass/abscess. (subgroup 2) The recommendation made in our national guideline (to perform direct appendectomy in this subgroup) is not in line with the available literature. A recent Cochrane review on this topic could only include two trials and stated that no firm conclusions could be drawn. An older systematic review, including 7 studies in children, concluded that non-operative treatment (NOT) led to fewer complications, specifically SSI and PAA, when compared to direct appendectomy. Still the recommendation from our national guideline is to perform a direct appendectomy based upon good experiences in the pediatric academic centers.~In order to investigate the optimal treatment for children with complex appendicitis we will perform a nationwide, multi-center, comparative, prospective cohort study. For the purpose of this study, treatment strategies will be standardized among the participating hospitals in order to reduce heterogeneity. Prospectively derived, high quality data will be sufficient to answer the research questions regarding the optimal treatment strategy for each subtype of complex appendicitis in the pediatric population. As it is a non-randomized prospective cohort study, propensity score matching technique will be performed in order to estimate the effect of the treatments adjusted for potential confounders.
Aim of this study is to evaluate the effect of different treatment strategies on overall complications, health related-Quality of Life (hr-QOL) and costs among two subtypes of complex appendicitis in children (<18 years old).~Main research questions: What is the difference in overall complications at three months between:~Subgroup 1 (complex appendicitis without abscess/mass formation): Laparoscopic (LA) and open appendectomy (OA) Subgroup 2: (complex appendicitis with abscess/mass formation): Non-operative treatment (NOT) and direct appendectomy