Original article
The Outcome of Laparoscopic Versus Open Appendectomy in Childhood
An Analysis of Routine Data Among 21 541 Children Insured by AOK
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Background: Appendectomy in children is performed either laparoscopically (LA) or by open surgery (OA). We studied whether, and how, the outcome is affected by the technique used and by the intraoperative conversion of LA to OA.
Methods: We analyzed routine data from children and adolescents in three age groups (1–5 years, 6–12 years, and 13–17 years) who were insured by the AOK statutory health insurance carrier in Germany and who underwent appendectomy in the period 2017–2019. General surgical complications and reoperations within 90 days were assessed with relevant indicators. Associations between the surgical technique and these indicators were studied with logistic regression.
Results: Of the 21 541 patients included in the study, general surgical complications were observed in 2.1% and reoperations in 1.8% overall. Broken down by age group, the corresponding figures were 5.4% and 4.4% (age 1 to 5), 2.5% and 1.8% (age 6 to 12), and 1.5% and 1.6% (age 13 to 17). The main risk factors for complications and reoperations were acute complicated appendicitis and conversion from LA to OA. Regression analysis revealed similar outcomes with OA compared to LA in the 1-to-5 age group, (odds ratios and 95% confidence intervals: 1.1 [0.6; 2.1] for general surgical complications and 1.5 [0.8; 2.7] for reoperations), but worse outcomes with OA in the other two age groups (age 6 to 12: 1.9 [1.2; 2.9] and 2.1 [1.5; 2.9]; age 13 to 17: 1.7 [1.0; 2.9] and 2.2 [1.4; 3.6]). When conversions were assigned to the LA group, the odds ratio (OA compared to LA) for reoperation across all age groups was 3.5 [2.8; 4.4] in patients with acute uncomplicated appendicitis and 4.2 [3.4; 5.3] in patients with complicated appendicitis. Complicated appendicitis also increased the rate of general surgical complications and the length of stay in hospital.
Conclusion: Among children in the two older age groups, LA was followed by fewer general surgical complications and reoperations than OA. These differences were less pronounced when conversions were counted as belonging to the LA group. Children aged 1–5 appear to benefit the least from the laparoscopic technique.
Appendectomy is one of the most common surgical procedures performed on children and adolescents (1). Since the 1980s, laparoscopic appendectomy (LA) has increasingly been performed instead of open appendectomy. LA is a safe procedure in patients with acute uncomplicated and acute complicated (perforated) appendicitis (2).
A recent meta-analysis revealed that LA is associated with less complications compared to the open procedure (3). However, increased rates of intraabdominal abscesses after LA compared to OA have also been reported (4, 5).
If intraoperatively complications or technical difficulties are encountered, a laparoscopic procedure may be converted to an open procedure in selected cases.
Piskun et al. (2001) showed in a case series of 52 patients that conversion of laparoscopic to open appendectomy was associated with an increase in postoperative morbidity (6).
As yet, conversions of LA to OA have not been systematically investigated. In the literature, conversions are commonly reported as a separate group. However, this approach results in the selection of high-risk patients from the group in whom appendectomy was started as a laparoscopic procedure. Since conversions are associated with the use of the laparoscopic technique, any resulting complications should be counted as belonging to the initial LA group. The randomized studies included in the meta-analysis of Neogi et al. (3), comparing laparoscopic and open appendectomy, did not take conversions of LA to OA into account.
The aim of our observational study was to find out whether there is an association between the surgical technique used for appendectomy (LA versus OA) and the postoperative outcome in pediatric patients. In addition, we investigated the effect of complications after conversions on the comparison of open and laparoscopic procedures. For this purpose, we performed separate analyses for three surgical techniques (laparoscopic versus open versus conversion) and for two surgical techniques (laparoscopic + conversion versus open) and then compared the respective results. In these analyses, we relied on routine data of the German statutory health insurance carrier AOK (Allgemeinen Ortskrankenkasse).
Methods
Data source
Our study is based on pseudonymized AOK routine data. These data cover hospital care diagnoses and procedures, drug prescriptions, length of hospital stay, and master data of the insured persons, such as age, gender and survival status.
Patients aged 1 to 17 years who underwent appendectomy (German Operation and Procedure Code [OPS]: 5–470) in the period 2017–2019 and in whom acute appendicitis (International Statistical Classification of Diseases and Related Health Problems [ICD]-10: K35) was documented as the primary diagnosis were included in the study. Pregnant women (ICD-10: O) as well as patients with malignant/in-situ neoplasms (ICD-10: C00-C97, D00-D09), Crohn‘s disease (ICD-10: K50), acute vascular disorders of intestine (ICD-10: K55.0), simultaneous appendectomy (OPS: 5–471), cholecystectomy (OPS: 5–4511), hysterectomy (OPS: 5–685, 5–685), oophorectomy/salpingo-oophorectomy (OPS: 5–652, 5–653), or intestinal reconstruction (OPS: 5–467. [3,4,6–9, a,x,y]) were excluded.
Endpoints
We assessed the endpoints “reoperations” and “general surgical complications”, both within a period of 90 days. The endpoints conformed to the definitions of the hospital quality indicators for appendectomy developed by the AOK Research Institute (WIdO, Wissenschaftliches Institut der AOK) (7).
Reoperations included unplanned treatment-related complications requiring intervention and surgery, such as restoration of intestinal continuity, bowel resection, peritoneal lavage, and surgical site revision (eTable 1 and 2). General surgical complications included surgical site complications, infection, sepsis, and transfusion (eTables 3 and 4).
The length of the initial hospital stay was measured in days
Statistical analysis
Descriptive statistics were calculated for the complete sample of cases and the groups LA (laparoscopic appendectomy, OPS: 5–470.1), OA (open appendectomy, OPS: 5–470. [0,x,y]) and intraoperative conversion of LA to OA (OPS: 5–470.2). Cases in which both LA and OA were documented were counted as belonging to the conversion group. In addition, patients were categorized according to age and stage of appendicitis. A distinction was made between acute complicated (ICD-10: K35.2, K35.31, K35.32) and acute uncomplicated (ICD-10: K35.30, K35.8) stage of appendicitis. Furthermore, based on age, it was differentiated between toddlers and preschoolers (1–5 years), school children (6–12 years), and adolescents (13, 14, 15, 16, 17). Differences between the groups were tested at a significance level of 5% using the Chi2 test for categorical data and the Kruskal-Wallis test for length-of-hospital-stay data. The key figures reported refer to the number of evaluable cases. Patients who could not be completely followed up and in whom no complication event occurred during the follow-up period were censored (reoperations: 317 cases, general surgical complications: 319 cases).
Multiple logistic regression analysis was used to determine the association of surgical technique with reoperations within 90 days and general surgical complications within 90 days. The association between surgical technique and length of hospital stay was assessed using multiple linear regression. The regression models included the surgical technique as an additional factor with simultaneous adjustment for age, gender and stage of appendicitis. All parameters were defined as dichotomous categorical variables. Age was defined using three parameters, as described above. Interaction terms were used to model the estimate of the effect of the surgical techniques within the various age groups. The logistic models used cluster-robust standard errors to account for hospital-related cluster effects. With the linear models, random intercepts for hospitals were used to account for cluster effects..
All analyses were performed using the STATA 16.0 (StataCorp, College Station, Texas) software.
Results
Frequencies of open and laparoscopic appendectomy by age and severity
Our study comprised 21 541 patients aged 1–17 years who underwent appendectomy in the period 2017–2019. Descriptive statistics are shown in Table 1. 87.2% of patients underwent laparoscopic appendectomy and 11.1% open appendectomy. Conversion of LA to OA occurred in 1.7% of patients. In the group of the 1– to 5-year-olds, open appendectomy was performed in 35.6% of cases, in the group of the 6– to 12-year-olds in 16.1% and among the 13– to 17-year-olds in 5.1%. The rates of conversion of LA to OA differed between the three groups: 5.4% in the 1-to-5 age group, 2% in the 6-to-12 age group and 1.2% in the 13-to-17 age group. OA was more frequently performed in complicated appendicitis (in 18.3%) compared to uncomplicated appendicitis (7.7%). Likewise, conversions of LA to OA were more commonly seen in complicated appendicitis compared to uncomplicated appendicitis (9.6% and 0.5%, respectively).
Female patients were less likely to have open appendectomy and conversion from LA to OA than male patients (37.4% versus 50.4% [p<0.001)] and 39.2% versus 50.4% [p<0.001], respectively). Table 2 shows the association between stage of appendicitis, age of patient and technique of appendectomy. The younger the patients, the more likely they were to have open appendectomy, regardless of the stage of appendicitis. OA was more frequently performed in patients with complicated appendicitis, regardless of patient age.
Surgery-related complications: Decreasing with increasing age and increasing with increasing severity
The non-adjusted endpoints are shown in eTable 5. Regardless of the surgical technique used, 1.9% of patients had to undergo reoperation within 90 days. In 2.1% of patients, a general surgical complication was observed within 90 days. The frequency of reoperation decreased with increasing age from 4.4% in the 1-to-5 age group to 1.8% in the 6-to-12 age group to 1.6% in the 13-to-17 age group. Likewise, the incidence of general surgical complications declined from 5.4% in patients aged 1–5 to above 2.5% in patients aged 6 to 12 to 1.5% in patients aged 13 to 17.
The univariate analysis found higher rates of reoperations and general surgical complications for OA and conversion of LA to OA compared to LA in the 6-to-12 and 13-to-17 age groups. In the 1-to-5 age group, higher rates of reoperations and complications were noted for conversion of LA to OA compared to laparoscopic surgery. However, no differences between open and laparoscopic technique were observed..
The median total length of hospital stay was four days for the total patient group. Irrespective of patient age, the length of hospital stay was longer for OA (4.5 days) and conversions (8 days) compared to LA (4 days). Furthermore, the length of hospital stay was longer in 1– to 5-year-old patients (6 days) compared to 6– to 12-year-old and 13– to 17-year-old patients (four days each).
Association of OA with complications and length of hospital stay in older children
The results presented above are not adjusted for the association of risk factors with the endpoints. The results of the risk-adjusted analysis are shown in Table 3 and Table 4.
Reoperations were associated with OA in the 6-to-12 and 13-to-17 age groups in comparison to LA (OR = 1.9 and 1.7, respectively). In the 6-to-12 and 13-to-17 age groups, conversion were also associated with reoperations (OR = 4.7 and 5.2, respectively). For the 1-to-5 age group, on the other hand, no association between surgical technique and reoperation was found. Moreover, acute complicated appendicitis was associated with reoperations (OR = 3.5).
General surgical complications were found to be associated with the use of the open surgical approach in the groups of patients aged 6 to 12 and 13 to 17 (OR = 2.0 and 2.3, respectively). In the three age groups, conversions were also positively associated with the incidence of general surgical complications (OR = 3.1, 2.9 and 6.8, respectively). Again, complicated appendicitis was identified as an additional risk factor in all age groups (OR = 2.7).
Length of hospital stay was associated with an open surgical approach (coefficient = 0.8, 0.5 and 0.8, respectively) and conversion (coefficient = 2.6, 3.0 and 3.2, respectively). Both surgical techniques prolonged the length of hospital stay. The same was observed for complicated appendicitis (coefficient = 3.2). The value of the coefficient corresponds to the mean change in the length of hospital stay in days (positive: prolongation, negative: shortening).
Inclusion of conversions in the laparoscopic appendectomy group
Since the need for conversion from LA to OA has to be regarded as a complication of the laparoscopic procedure, we carried out a logistic regression analysis of the dataset obtained by counting patients with conversion as belonging to the laparoscopic group. The results are shown in Table 5 and Table 6.
This change resulted in consistently lower odds ratios for OA with respect to 90-day reoperations and 90-day complications compared to the initial analysis. In the 13-to-17 group, no difference was found between open and laparoscopic technique for 90-day reoperations. On the other hand, complicated appendicitis remained a strong risk factor for reoperations, general surgical complications and length of hospital stay.
Discussion
In this study, we investigated the effect the surgical approach had on the frequencies of 90-day reoperations and 90-day general surgical complications as well as the length of hospital stay in 21 541 appendectomies performed on children and adolescents. After risk adjustment, our analysis showed that OA was associated with frequency of complications and increase in the length of hospital stay. However, in children aged 1–5, no difference between open and laparoscopic technique was found in the rates of 90-day reoperations and 90-day general surgical complications.
The main risk factors for complications and increased length of hospital stay were the presence of complicated appendicitis and conversion from OA to LA. The inclusion of conversions in the laparoscopic group led to a reduction in the odds ratios for OA. As a result, no association between OA and 90-day reoperation rate was found in adolescents (13–17 years).
The outcomes for LA compared to OA have already been investigated in previous studies among adults, children and adolescents. While some studies showed no differences between LA and OA with regard to postoperative abscesses, surgical site infections, hospital readmissions and length of hospital stay (8, 9), other authors reported for LA a decrease in surgical site infections and length of hospital stay (10, 11, 12). The latter findings are in line with the outcomes observed by us, since we also found less complications and shorter hospital stays after LA. However, these differences were not seen in the youngest age group (1–5 years).
Our previous study showed a clear trend that young children (1–5 years) with acute complicated appendicitis frequently were treated with open appendectomy (7). Thus, a certain bias may exist with regard to this patient group.
In adults, the available literature clearly shows an advantage of the laparoscopic approach with regard to a reduction in complications of wound healing (5, 13, 14, 15, 16, 17). However, Ingraham et al. found an increased risk of surgery-related inflammations in patients who underwent LA for complicated appendicitis (17).
The outcomes reported for intra-abdominal abscesses are also inconsistent. Some studies showed an increased risk of developing intraabdominal abscesses for LA compared to OA (14, 16). However, other analyses were unable to confirm this finding (5, 9, 13, 18, 19).
Furthermore, several studies found that the length of hospital stay was shorter in patients with LA compared to OA (10, 13, 14). For the 13-to-17 age group, our findings are consistent with the literature.
An important aspect of our study was the inclusion of conversions in the laparoscopic group. Conversion from laparoscopic to open surgery is usually required due to intraoperative difficulties and thus a major risk factor for complications. As expected, the combined analysis of conversion and LA resulted in a reduced association of the open procedure with the occurrence of general surgical complications when comparing OA and LA. Omling et al. made the same observation for the risk of postoperative small bowel obstruction. Laparoscopic appendectomy was only superior to open appendectomy if conversions were excluded (12).
Finnerty et al. investigated the risk factors for conversion in adults. The strongest risk factor was complicated appendicitis (20). In a study among children and adolescents, Johnson et al. found higher conversion rates in patients with peritonitis, abscess, obesity, and an age of 13 years or older (21). This finding is confirmed by our study in which the conversion rate was higher in patients with complicated appendicitis compared to patients with uncomplicated appendicitis (Table 2). However, our study found a decreasing conversion rate with increasing age (Table 2).
Overall, our results showed that laparoscopic appendectomy is not necessarily the best option for all patients. Particularly in younger patients, conversions of laparoscopic to open surgery frequently led to complications. We demonstrated that the youngest patient group (1–5 years) benefited the least from a laparoscopic approach.
Limitations
Our study has several limitations. First, our results stem from a secondary data analysis based on routine data. Thus, coding inaccuracies cannot be ruled out. In Germany, on the other hand, CD-10 und OPS documentation is standardized by coding guidelines and subject to ongoing controls (22).
Second, only those complication events could be included in the analysis that were validly represented through the catalog systems. As described above, the reported complication rates are well in line with those in the literature. Furthermore, the stages of appendicitis and the various surgical techniques used for appendectomy are well represented in the coding system.
Third, our study is a purely observational study without randomization. Ideally, the associations presented above should be verified in randomized trials. Yet, the reported rates of occurrence reflect the reality of care in Germany based on current data.
In addition, there are limitations with regard to generalizability of the findings since the investigated patient population was exclusively composed of children and adolescents insured by AOK. Despite the fact that the group of AOK insured persons accounts for about one third of all hospital cases in Germany, there are certain differences to the insured populations of other health insurance funds in terms of age structure and comorbidity (23). However, this effect is very limited in our study, since we exclusively looked at children and adolescents. It is reasonable to assume that the associations between age, appendicitis stage, surgical technique, and complications investigated in our study are independent of the study population.
Conclusion
Our study shows that laparoscopic appendectomy is associated with lower complication rates and shorter length of hospital stay compared to open appendectomy. The inclusion of cases of conversion in the laparoscopic group reduced the advantages of the laparoscopic approach. As a result, a reduction in risk of complications was no longer demonstrated for very young children who underwent laparoscopic appendectomy. Thus, especially in the 1-to-5 age group, the decision to perform a laparoscopic appendectomy should be weighed against the risk of conversion.
Conflict of interest statement
WOB is member of the “Expert Panel Abdominal Surgery“ of the Quality Assurance with Routine Data (QSR) of the AOK Research Institute (WIdO).
The remaining authors declare no conflict of interest.
Manuscript received on 2 June 2023, revised version accepted on 23 October 2023
Translated from the original German by Ralf Thoene, M.D.
Corresponding author
Prof. Dr. med. Udo Rolle
Klinik für Kinderchirurgie und Kinderurologie
Universitätsklinikum Frankfurt/Main
Theodor-Stern-Kai 7
60590 Frankfurt, Germany
udorolle@yahoo.com
Cite this as:
Rolle U, Bechstein WO, Fahlenbrach C, Heller G, Meyer HJ, Schuler E, Stier A, Waibel B, Jeschke E, Günster C, Maneck M: The outcome of laparoscopic versus open appendectomy in childhood—an analysis of routine data among 21 541 children insured by AOK. Dtsch Arztebl Int 2024; 121: 39–44. DOI: 10.3238/arztebl.m2023.0234
Department of General, Visceral, Transplantation and Thoracic Surgery, University Hospital Frankfurt/Main, Frankfurt/Main, Germany: Prof. Dr. med. Wolf O. Bechstein
AOK Federal Association, Berlin, Germany: Dr. med. Claus Fahlenbrach
Institute for Quality Assurance and Transparency in Healthcare (IQTIG), Berlin, Germany: PD Dr. med. Günther Heller
German Society of Surgery (DGCH), Berlin, Germany: Prof. Dr. med. Dr. h. c. Hans-Joachim Meyer
Helios Kliniken, Division of Quality Management, Berlin, Germany: Dr. med. Ekkehard Schuler
Department of General and Visceral Surgery, HELIOS Hospital Erfurt, Erfurt, Germany: Prof. Dr. med. Albrecht Stier
Medical Service of the Health Insurance Fund Baden-Württemberg, Freiburg, Germany: Dr. med. Beate Waibel
AOK Research Institute (WIdO), Berlin, Germany: Dr. rer. nat. Elke Jeschke, Christian Günster, Dr. rer. nat. Matthias Maneck
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