The impact of obesity on laparoscopic appendectomy: Results from the ACS National Surgical Quality Improvement Program pediatric database

    The Impact of Obesity on Laparoscopic Appendectomy: Results from the ACS National Surgical Quality Improvement Program Pediatric Database Maria Michailidou, Maria G. Sacco Casamassima, Seth D. Goldstein, Colin Gause, Omar Karim, Jose H. Salazar, Jingyan Yang, Fizan Abdullah PII: DOI: Reference:

S0022-3468(15)00404-2 doi: 10.1016/j.jpedsurg.2015.07.005 YJPSU 57280

To appear in:

Journal of Pediatric Surgery

Received date: Revised date: Accepted date:

26 December 2014 30 June 2015 3 July 2015

Please cite this article as: Michailidou Maria, Sacco Casamassima Maria G., Goldstein Seth D., Gause Colin, Karim Omar, Salazar Jose H., Yang Jingyan, Abdullah Fizan, The Impact of Obesity on Laparoscopic Appendectomy: Results from the ACS National Surgical Quality Improvement Program Pediatric Database, Journal of Pediatric Surgery (2015), doi: 10.1016/j.jpedsurg.2015.07.005

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ACCEPTED MANUSCRIPT

The Impact of Obesity on Laparoscopic Appendectomy: Results from the ACS National Surgical

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Quality Improvement Program Pediatric Database.

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Maria Michailidou, MD1; Maria G. Sacco Casamassima, MD1; Seth D. Goldstein, MD1; Colin Gause,

Center for Pediatric Surgical Clinical Trials and Outcomes Research, Division of Pediatric, Surgery,

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MD1; Omar Karim, MD1; Jose H. Salazar, MD1; Jingyan Yang, MHS2, Fizan Abdullah, MD, PhD1

Johns Hopkins University School of Medicine, Baltimore, Maryland Department of Epidemiology, Mailman School of Public Health, Columbia University

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Address Correspondence to: Fizan Abdullah, MD, PhD

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Johns Hopkins University School of Medicine

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Baltimore, MD 21287

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Bloomberg Children’s Center, Suite 7337

e-mail: [email protected] Tel (410) 955-1983 Fax (410) 502-5314

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ACCEPTED MANUSCRIPT Abstract Background

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Childhood obesity is a worsening epidemic. Little is known about the impact of elevated BMI on perioperative and postoperative complications in children who undergo laparoscopic surgery. The purpose

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of this study was to examine the effects of obesity on surgical outcomes in children using laparoscopic

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appendectomy as a model for the broader field of laparoscopic surgery.

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Study Design

Using the Pediatric National Surgical Quality Improvement Program (NSQIP) data from 2012, patients

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aged 2-18 years old with acute uncomplicated and complicated appendicitis who underwent laparoscopic

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appendectomy were identified. Children with a Body Mass Index (BMI) ≥ 95th percentile for their age and gender were considered obese. Primary outcomes, including overall morbidity and wound

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complications, were compared between non-obese and obese children. Multivariate regression analysis

Results

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was conducted to identify the impact of obesity on outcome.

A total of 2,812 children with acute appendicitis who underwent appendectomy were included in the analysis; 22% were obese. Obese children had longer operative times but did not suffer increased postoperative complications when controlling for confounders (OR 1.3, 95% CI: 0.83–0.072 for overall complications, OR 1.3, 95 % CI: 0.84-1.95 for wound complications). Conclusions Obesity is not an independent risk factor for postoperative complications following laparoscopic

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ACCEPTED MANUSCRIPT appendectomy. Although operative times are increased in obese children, obesity does not increase the likelihood of 30-day postoperative complications.

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Keywords: NSQIP; Pediatric; Obesity; Laparoscopic appendectomy; Outcomes

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ACCEPTED MANUSCRIPT Introduction1 The incidence of childhood obesity has increased dramatically over the past two decades. Data

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from the National Health and Nutrition Examination Survey showed that in the year 2012, more than one

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third of American children and adolescents were obese [1]. As the prevalence of obesity in this patient population continues to rise, pediatric surgeons will be faced with having to perform an increasing

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number of both emergent and elective surgeries on overweight children. Therefore it is important for surgeons to select the approach that will optimize outcomes in obese patients.

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Obesity is associated with numerous potential comorbidities, including respiratory disorders,

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hypertension, and diabetes [2-5] . Operations on these patients are often more challenging, owing to poor operative exposure and increased technical difficulties. Additionally, the excess visceral adipose tissue seems to favor a pro-inflammatory state and contributes to metabolic disturbances in these patients [6].

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This may influence the post-operative immune response and account for some of the adverse post-surgical

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outcomes, including surgical site infection (SSI) and venous thromboembolism (VTE) [7,8]. Obesity is thus perceived as a risk factor for adverse intraoperative and postoperative outcomes in these patients [6].

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The knowledge of procedure-specific risk associated with obesity is important for the establishment of outcome standards that accurately reflect expected results.

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Acute appendicitis is one of the most common surgical emergencies in pediatric patients. However, the impact of obesity on pediatric patients undergoing laparoscopic surgery has not been extensively investigated. This study seeks to use laparoscopic appendectomy as a proxy for the broader field of laparoscopic surgery in order to draw conclusions regarding associated postoperative outcomes. The current literature is inconclusive and the results are not readily generalizable as they are based on small single institutional series [9-11]. Our study aimed to clarify the relationship between obesity and the risk of postoperative morbidity following laparoscopic appendectomy by using a large, prospectively collected, multi-institutional dataset - the American College of Surgeons (ACS) Pediatric National 1

Abbreviations: SSI: Surgical site infection, VTE: venous thromboembolism, ACS: American College of Surgeons, NSQIP: National Surgical Quality Improvement Program, LA: Laparoscopic appendectomy, LOS: Length of stay

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ACCEPTED MANUSCRIPT Surgical Quality Improvement Program (NSQIP-Pediatric). We hypothesized that obesity would

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contribute to an increase in overall morbidity and, in particular, infectious complications.

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1. Materials and Methods 1.1. Data source and study population

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The study was performed using data from the ACS NSQIP Pediatric Participant Use Data File (PUF) from 2012, with data from 50 participating institutions collected in the period from January 1st

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2012 to December 31st 2012. The population consisted of patients aged 2 to 18 years who underwent

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laparoscopic appendectomy (LA) for acute appendicitis as their primary operative procedure (Current Procedural Terminology-CPT-code 44970). The diagnosis of complicated and uncomplicated appendicitis was determined by International Classification of Diseases, Ninth Revision (ICD – 9) codes.

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Cases coded as 540 (acute appendicitis) and 540.9 (acute appendicitis without peritonitis) were

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considered uncomplicated, and cases coded as 540.0 (acute appendicitis with generalized peritonitis), and 540.1 (acute appendicitis with peritoneal abscess) were considered as complicated. Exclusion criteria

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were: elective case type; interval appendectomy; missing body mass index (BMI) and BMI outlier. BMI was considered an outlier value when under 10 Kg/m2 or over 100 Kg/m2 , as these values were

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considered as biological implausible values (BIV), likely due to inaccuracies in reporting height, weight, and age. BMI was calculated for each patient with a documented weight and height. Based on the Centers for Disease Control and Prevention (CDC) guidelines, patients with a BMI over the 95th percentile for their age and gender were considered obese [12]. Considering the reported increased risk for postoperative complications in underweight children [13], a sensitivity analysis on outcomes was performed by excluding an underweight group with a BMI less than the 5th percentile. Demographics, preoperative risk factors, appendiceal perforation rates, and outcomes were compared between the obese and non-obese groups.

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ACCEPTED MANUSCRIPT 1.2. Outcome variables The primary outcomes of interest were 30-day mortality and overall morbidity. This composite

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variable was defined as having at least one of the following complications: superficial, deep or organ

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space surgical site infections, wound disruption, pneumonia, unplanned intubation, pulmonary embolism, progressive renal insufficiency, acute renal failure, urinary tract infection, coma > 24 hours, stroke or

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intracranial hemorrhage, seizure disorder, cardiac arrest, transfusion, venous thromboembolism, sepsis, and central line associated blood stream infection.

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Secondary outcomes of interest included wound complication, operative time, anesthesia time

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(defined as time from anesthesia induction to recovery), total length of hospital stay (LOS) (defined as time from admission to discharge), days from operation to discharge, readmissions, and reoperations. The secondary composite variable, wound complication, was defined as having at least one of the following

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wound occurrences: superficial, deep or organ space SSI, or wound disruption. Patients were excluded for

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experiencing a complication if the condition was documented preoperatively (e.g. pneumonia present

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preoperatively).

1.3. Statistical analysis

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Descriptive analyses were conducted using the Chi-squared test for categorical outcomes and student’s t-test and Wilcoxon rank sum test for means and medians of continuous data, respectively. A subset analysis was performed to compare outcomes of obese and non-obese patients presenting with uncomplicated and complicated appendicitis. Multivariate regression analysis was performed to assess the risk-adjusted influence of obesity on overall post-operative complications and wound complications. The multivariate analysis controlled for demographics, preoperative risk factors, ASA class, preoperative leukocytosis, and diagnosis of complicated appendicitis. All covariates with p <0.2 based on univariate analysis were entered into the regression model. Statistical analysis was performed using STATA Statistical Software (Version 12.1, Stata Corp). A p value < 0.05 was considered statistically significant.

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ACCEPTED MANUSCRIPT 2. Results 2.1. Study population and demographics

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During the study period, a total of 5,741 patients were registered in the NSQIP Pediatric PUF

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with a procedural code indicating appendectomy. Excluded from the analysis were 2,929 patients with missing BMI data, outlier BMI, younger than 2 years of age, and cases performed in an elective setting

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(Figure 1). The study population consisted of 2,812 patients that met inclusion criteria. There were 2,189 (77.8%) non-obese and 634 (22.5%) obese patients. Demographic characteristics and preoperative risk

2.2. Obesity and associated complications

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factors are displayed in table 1.

Obese children were mostly male (66.5% vs. 58.3%, p < 0.001) and more often assigned an ASA

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classification of mild or severe disturbance when compared to their peers (Table 1). Obese patients

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presented more often with complicated appendicitis (27.1% vs. 23. 4%, p = 0.052). All procedures except one were completed laparoscopically. Unadjusted overall complications were similar between the two

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groups. Although not statistically significant, there was a trend toward increased rate of wound-related complications in the obese group. Eighty-four non-obese patients (3.84%) and thirty-four obese (5.46%)

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patients suffered wound complications (p=0.075). Obese patients experienced more deep incisional SSI when compared with non-obese patients (p=0.04). There were no differences in organ space SSI occurrence between the two groups (p=0.4). Non-wound related complications were observed in fourteen non-obese patients (0.64%) and in eight obese patients (1.3%), respectively (p=0.107) (Table 2). The most common non-wound related complication was pneumonia, observed in six non-obese patients (0.3%) and six obese patients (0.95%) (p=0.020). In the subset analysis of uncomplicated and complicated appendicitis, anesthesia and operative times were longer in the obese group. The mean difference in operative time between obese and non-obese patients was 7.7 minutes (p=0.02) in complicated appendicitis (Table 3). No difference was observed in mean total LOS or days from operation to hospital discharge. Likewise, overall complications and wound related complications were

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ACCEPTED MANUSCRIPT similar. Readmission and reoperation rates were comparable between the two groups (Table 3). Table 4 describes the adjusted multivariate analysis for perioperative outcomes. Perforated appendicitis and ASA

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class IV and V were significant independent risk factors for postoperative wound complications and

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overall complications. After adjusting for multiple confounding factors, obese patients did not have a higher likelihood of developing wound related complications and overall complications (wound

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complications: OR 1.28, 95% CI: 0.84-1.97; p=0.24; overall complications: OR 1.25, 95% CI: 0.82-1.91;

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p=0.29). No mortality was observed in this cohort.

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Discussion

This analysis of a large multicenter pediatric dataset was performed to clarify the conflicting findings of past studies regarding the impact of obesity on postsurgical outcomes. Appendectomy is the

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most common general surgery operation in the pediatric population and was accordingly chosen as the

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focus of this investigation. In this study, we found that obesity is not a risk factor for postoperative complications in pediatric patients undergoing laparoscopic appendectomy. Although there was a trend

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towards an increased rate of wound and overall complications in obese patients, these differences were not significant after adjusting for complicated appendicitis and preoperative risk factors.

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Laparoscopic appendectomy (LA) is increasingly being performed in the United States, currently comprising 80% of all appendectomies [14,15]. Although several studies have demonstrated that the laparoscopic approach offers significant advantages to obese patients, in terms of shorter LOS and reduced incidence of wound infections [16-23], many surgeons may remain reluctant to perform LA in obese patients particularly in the setting of complicated appendicitis [24]. One of the possible explanations is that LA appears associated with an increased risk of intra-abdominal abscess formation [14,15,18,25,26]. Wound complications and intra-abdominal abscess are more often observed in patients with complicated appendicitis [27]. As a higher rate of preoperative sepsis and perforated appendicitis is observed in obese patients, these patients may theoretically have an increased risk of postoperative wound complications and intra-abdominal abscess [9,16,18]. Obesity is known to induce a broad array of

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ACCEPTED MANUSCRIPT changes in expression of hormones and cytokines, and interacts on multiple levels with the immune system [28]. The increased rates of preoperative sepsis in obese patients have been therefore attributed to

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an impaired immune response [24]. Moreover, atypical presentation, unreliable physical examination and

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decreased sensitivity of diagnostic imaging in detecting acute appendicitis may be responsible for delayed presentation, leading to an increased rate of perforated appendicitis in this population [11,29]. In this

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review we did not observe an increased rate of preoperative sepsis in obese patients; however, there was a trend toward increased rate of complicated appendicitis in this group.

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Currently, scant literature exists to accurately assess the extent to which obesity affects surgical

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outcomes following laparoscopic appendectomy in children. The few existing studies addressing the impact of obesity on surgical outcomes after appendectomy in children compare outcomes of LA and OA [10,11,30,31]. All but one are retrospective small series which have yielded conflicting results regarding

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the benefit of laparoscopic appendectomy in obese children [10,11,30,31]. Discrepancies among the

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literature may be partially explained by heterogeneity in the definition of obesity, as the weight percentile was often used rather than the BMI [10,11]. The use of weight percentile not adjusted for height

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potentially overestimates obesity in children and incorrectly analyzes the effect of obesity on outcomes [32]. In this study, to exclude possible bias related to the misclassification of patients as obese, we

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excluded patients with incomplete or outlier BMI from the analysis. In a prospective study analyzing outcomes after laparoscopic appendectomy in obese children with perforated appendicitis, obesity was associated with prolonged hospitalization which the authors attribute to an increased rate of intra-abdominal abscess formation [30]. Conversely, other studies have reported similar rates of intra-abdominal abscess formation in non-obese and obese children undergoing laparoscopic appendectomy [29,33]. This finding was confirmed by our study; in this series obesity was not correlated with an increased rate of intra-abdominal abscess formation. Childhood obesity is known to increase perioperative adverse respiratory events, as this population presents with a higher prevalence of pulmonary co-morbidities such as asthma and obstructive sleep apnea syndrome [34]. Obese patients have a predisposition to hypercapnia due to increased oxygen

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ACCEPTED MANUSCRIPT consumption and carbon dioxide production. In addition, the excess body fat around the ribs, chest, under the diaphragm, and within the abdominal cavity contributes to reduced chest wall compliance, favoring

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pneumonia was significantly higher in the obese group in this study.

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postoperative atelectasis and pneumonia [34]. Consistent with these observations, the occurrence of

Finally, body habitus in obese patients can contribute to a more challenging surgical procedure.

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Access to the abdominal cavity may be more difficult, due to the thick fatty layer of the abdominal wall and the more caudal position of the umbilicus in respect to the aortic bifurcation. Although major

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complications during laparoscopic entry are rare [35], anatomical changes related to obesity may

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hypothetically increase these risks. During laparoscopy, surgeons work in a confined space, therefore exposure of the surgical field may be more challenging in obese patients due to the excess visceral fat and redundant bowel, potentially necessitating an additional instrumentation port for retraction. [28].

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Operative time is thus generally used as an objective marker for operative difficulties. Longer operative

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times have previously been reported in obese pediatric patients undergoing LA [30,36]. This data is confirmed by the present study. In obese patients, the mean operative time increased by a mean of 3.4

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minutes in uncomplicated appendicitis and 7.7 minutes in complicated appendicitis. This study must be interpreted in light of several limitations. One limitation is that this analysis

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includes only patients treated at ACS NSQIP participating hospitals, which may limit the generalizability of our results. Due to the systematic sampling-strategy, the number of participating institutions, and the limitation of the study period to one calendar year, the sample size may be underpowered in detecting significant differences between obese and non-obese patients. Moreover, given the relatively small number of observed complications in this study, it was not possible perform a subgroup analysis to compare morbidity between moderately and severely obese patients. Another limitation of this study is the fact that there is a complex interaction between obesity and other preoperative independent risk factors for postoperative complications. However, this effect is mitigated by the use of multivariate adjustment, which allows us to control for possible relationships between dependent variables and examine the effect of each. Additionally, we observed a large number of missing height data as well as

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ACCEPTED MANUSCRIPT outlier BMIs; consequently we excluded a large number of patients from the analysis. As previously reported [37], we found certain inaccuracies in wound classification, as 2.5% of cases were mislabeled as

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clean cases. Finally, another limitation of our study is the lack of follow-up beyond 30 postoperative days.

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Complications that are likely to occur in a delayed fashion, such as incisional hernias, are thus not captured. Despite these limitations, we believe that the use of a surgically oriented database, as well as the

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large number of patients analyzed in this study, represents a valuable addition to the small amount of data available on this topic.

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In conclusion, obesity is not a contraindication to laparoscopic appendectomy in cases of complicated

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appendicitis, as the rate of wound occurrence and intra-abdominal abscess formation in these patients is comparable with that of non-obese patients. Although obesity is associated with a moderate increase in operative time, these differences are clinically irrelevant. This data supports that the selection of the

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procedure for acute appendicitis should be based on the surgical experience with the open or laparoscopic

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technique, rather than on the patient body habitus.

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[8] Bamgbade OA, Rutter TW, Nafiu OO, et al: Postoperative complications in obese and nonobese patients. World J.Surg. 2007;31:556-60; discussion 561 [9] Blanco FC, Sandler AD, Nadler EP: Increased incidence of perforated appendicitis in children with obesity. Clin.Pediatr.(Phila) 2012;51:928-932 [10] Davies DA, Yanchar NL: Appendicitis in the obese child. J.Pediatr.Surg. 2007;42:857-861 [11] Kutasy B, Puri P: Appendicitis in obese children. Pediatr.Surg.Int. 2013;29:537-544 [12] http://www.cdc.gov/healthyyouth/obesity/fscts.htm. 2014;

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ACCEPTED MANUSCRIPT [13] Stey AM, Moss RL, Kraemer K, et al: The importance of extreme weight percentile in postoperative morbidity in children. J.Am.Coll.Surg. 2014;218:988-996

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[14] Senekjian L, Nirula R: Tailoring the operative approach for appendicitis to the patient: a prediction

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model from national surgical quality improvement program data. J.Am.Coll.Surg. 2013;216:34-40 [15] Markar SR, Blackburn S, Cobb R, et al: Laparoscopic versus open appendectomy for complicated

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and uncomplicated appendicitis in children. J.Gastrointest.Surg. 2012;16:1993-2004 [16] Mason RJ, Moazzez A, Moroney JR, et al: Laparoscopic vs open appendectomy in obese patients:

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outcomes using the American College of Surgeons National Surgical Quality Improvement Program

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database. J.Am.Coll.Surg. 2012;215:88-99; discussion 99-100

[17] Ingraham AM, Cohen ME, Bilimoria KY, et al: Comparison of outcomes after laparoscopic versus open appendectomy for acute appendicitis at 222 ACS NSQIP hospitals. Surgery 2010;148:625-35;

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discussion 635-7

[18] Masoomi H, Nguyen NT, Dolich MO, et al: Comparison of laparoscopic versus open appendectomy

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for acute nonperforated and perforated appendicitis in the obese population. Am.J.Surg. 2011;202:733-8;

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discussion 738-9

[19] Varela JE, Hinojosa MW, Nguyen NT: Laparoscopy should be the approach of choice for acute

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appendicitis in the morbidly obese. Am.J.Surg. 2008;196:218-222 [20] Corneille MG, Steigelman MB, Myers JG, et al: Laparoscopic appendectomy is superior to open appendectomy in obese patients. Am.J.Surg. 2007;194:877-80; discussion 880-1 [21] Clarke T, Katkhouda N, Mason RJ, et al: Laparoscopic versus open appendectomy for the obese patient: a subset analysis from a prospective, randomized, double-blind study. Surg.Endosc. 2011;25:1276-1280 [22] Towfigh S, Chen F, Katkhouda N, et al: Obesity should not influence the management of appendicitis. Surg.Endosc. 2008;22:2601-2605 [23] Enochsson L, Hellberg A, Rudberg C, et al: Laparoscopic vs open appendectomy in overweight patients. Surg.Endosc. 2001;15:387-392

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ACCEPTED MANUSCRIPT [24] Mason RJ, Mason AJ: Open-close case? New data on appendectomy in an obese patient cohort. Expert Rev.Gastroenterol.Hepatol. 2013;7:1-3

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[25] Sauerland S, Jaschinski T, Neugebauer EA: Laparoscopic versus open surgery for suspected

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appendicitis. Cochrane Database Syst.Rev. 2010;(10):CD001546. doi:CD001546

[26] Henry MC, Walker A, Silverman BL, et al: Risk factors for the development of abdominal abscess

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following operation for perforated appendicitis in children: a multicenter case-control study. Arch.Surg. 2007;142:236-41; discussion 241

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[27] Wang X, Zhang W, Yang X, et al: Complicated appendicitis in children: is laparoscopic appendectomy appropriate? A comparative study with the open appendectomy--our experience.

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[28] Mullen JT, Moorman DW, Davenport DL: The obesity paradox: body mass index and outcomes in

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patients undergoing nonbariatric general surgery. Ann.Surg. 2009;250:166-172 [29] Sulowski C, Doria AS, Langer JC, et al: Clinical outcomes in obese and normal-weight children

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undergoing ultrasound for suspected appendicitis. Acad.Emerg.Med. 2011;18:167-173

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[30] Garey CL, Laituri CA, Little DC, et al: Outcomes of perforated appendicitis in obese and nonobese children. J.Pediatr.Surg. 2011;46:2346-2348

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[31] Fraser JD, Garey CL, Laituri CA, et al: Outcomes of laparoscopic and open total colectomy in the pediatric population. J.Laparoendosc.Adv.Surg.Tech.A 2010;20:659-660 [32] Valerio G, Scalfi L, De Martino C, et al: Comparison between different methods to assess the prevalence of obesity in a sample of Italian children. J.Pediatr.Endocrinol.Metab. 2003;16:211-216 [33] Yannam GR, Griffin R, Anderson SA, et al: Single incision pediatric endosurgery (SIPES) appendectomy--is obesity a contraindication? J.Pediatr.Surg. 2013;48:1399-1404 [34] Tait AR, Voepel-Lewis T, Burke C, et al: Incidence and risk factors for perioperative adverse respiratory events in children who are obese. Anesthesiology 2008;108:375-380 [35] Ahmad G, O'Flynn H, Duffy JM, et al: Laparoscopic entry techniques. Cochrane Database Syst.Rev. 2012;2:CD006583

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ACCEPTED MANUSCRIPT [36] Knott EM, Gasior AC, Holcomb GW,3rd, et al: Impact of body habitus on single-site laparoscopic appendectomy for nonperforated appendicitis: subset analysis from a prospective, randomized trial.

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J.Laparoendosc.Adv.Surg.Tech.A 2012;22:404-407

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[37] Sharp NE, Knott EM, Iqbal CW, et al: Accuracy of American College of Surgeons National Surgical Quality Improvement Program Pediatric for laparoscopic appendectomy at a single institution.

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J.Surg.Res. 2013;184:318-321

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Obese

Variable

(n = 2,189)

(n = 623)

Age, years, mean ± SD

11.3 ± 3.7

11.0 ± 3.5

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Non obese

28 (1.28)

P value 0.043 0.345

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Age, years, n (%) ≤3

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Table 1 Demographics, preoperative and intraoperative risk factors and disease characteristics of non-obese and obese pediatric patients undergoing laparoscopic appendectomy

5 (0.8)

>3≤8

401 (18.32)

9 ≤ 15

1,380 (63.04)

392 (62.92)

380 (17.36)

97 (15.57)

1, 275 (58.3)

414 (66.5)

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129 (20.71)

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> 15

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Male gender, n (%) Race, n (%) White

1, 727 (78.89)

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Black

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Asian Other

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Unknown

469 (75.28)

186 (8.50)

69(11.08)

54 (2.47)

10 (1.61)

8 (0.37)

2 (0.32)

214 (9.78)

73 (11.72)

ASA classification, n (%) 1 No disturbance

< 0.001 0.101

< 0.001 1, 242 (56.74)

273 (43.82)

2 Mild disturbance

837 (38.24)

307 (49.28)

3 Severe disturbance

103 (4.71)

42(6.74)

4 Life threatening

1 (0.05)

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None assigned

6 (0.27)

1 (0.16)

11 (0.50)

4 (0.64)

0.673

113 (5.16)

55 (8.83)

0.001

Pre-operative risk factors, n (%) Diabetes Pulmonary risk factors, †

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ACCEPTED MANUSCRIPT Cardiac risk factors

29 (1.32)

Renal risk factors ‡

5 (0.23)

9 (1.44)

0.819

-

0.232 0.309

66 (3.02)

14 (2.25)

Immunocompromised ¥

19 (0.87)

6 (0.96)

Chemotherapy / Radiation

7 (0.32)

2 (0.32)

0.996

Bleeding/ Hematologic disorder

17 (0.78)

9 (1.44)

0.124

774 (35.36) 14.58 ± 5.23

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Wound classification, n (%) Clean Clean/ Contaminated

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Dirty/ Infected Complicated appendicitis, n (%)

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15.25 ± 5.18

0.823

0.312 0.009 0.131

60 (2.74)

10 (1.61)

545 (24.90)

146 (23.43)

1, 079 (49.29)

301 (48.31)

505 (23.07)

166 (26.65)

511 (23.34)

169 (27.13)

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Contaminated

234 (37.56)

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Pre-operative WBC, mean ± SD*

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SIRS/Sepsis/Septic shock

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Neurological deficit ⱡ

0.052

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SIRS: Systemic inflammatory response; ASA: American society of anesthesiologists; *Available for 2,450 (87%) of patients; † Current pneumonia, history of asthma, history of cystic fibrosis, bronchopulmonary dysplasia, oxygen support, tracheostomy, structural pulmonary/ airway abnormality ‡ Acute renal failure, currently on dialysis ⱡ Coma > 24 hours, developmental delay, seizure disorder, cerebral palsy, neuromuscular disease, structural CNS abnormality, intraventricular hemorrhage ¥ Steroid use, solid organ transplant, bone marrow transplant, immune disease

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ACCEPTED MANUSCRIPT

Table 2. Unadjusted outcomes of non obese and obese pediatric patients undergoing

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laparoscopic appendectomy

(n = 2,189)

Wound complications, n (%)

84 (3.84)

(n = 623)

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Outcome

Obese

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Non obese

P value

34 (5.46)

0.075

10 (1.61)

0.061

3 (0.48)

0.041

64 (2.92)

22 (3.53)

0.437

5 (0.23)

1 (0.16)

0.746

14 (0.64)

8 (1.28)

0.107

6 (0.27)

6 (0.96)

0.020

Unplanned intubation, n (%)

-

1 (0.16)

0.061

Urinary tract infection, n (%)

1 (0.05)

-

0.594

Sepsis, n (%)

3 (0.14)

2 (0.32)

0.336

Bleeding, n (%)

4 (0.18)

-

0.286

Seizure, n (%)

2 (0.10)

-

0.450

17 (0.78)

NU

Superficial SSI, n (%)

2 (0.09)

MA

Deep incisional SSI, n (%) Organ/space SSI, n (%)

ED

Wound disruption, n (%) Non-wound related complications, n

PT

(%)

AC

CE

Pneumonia, n (%)

* No reported complications were observed in the following: pulmonary embolism, venous thrombooembolism, progressive renal insufficiency, acute renal failure, coma > 24hours, CVA/Stroke or intracranial hemorrhage, cardiac arrest, central line associated blood stream infection

18

ACCEPTED MANUSCRIPT Table 3. Outcomes of non obese and obese pediatric patients undergoing laparoscopic appendectomy for complicated and uncomplicated appendicitis Complicated appendicitis (n =

2,132)

680)

Outcome

= 1,678)

= 454)

Overall complications, n (%)

37 (2.2)

13 (2.9)

P

Non obese

Obese (n

(n = 511)

= 169)

59 (11.6)

26 (15.4)

RI P

Obese (n

value

SC

Non obese (n

T

Uncomplicated appendicitis (n =

0.411

27 (1.6)

11 (2.4)

NU

Wound complications, n (%)

Anesthesia time, min, mean

87.1 ± 78.2

80.5

Operative time, min, mean ±

ED

± SD

89.5 ±

41.2 ± 23.6

57 (11.2)

23 (13.6)

CE

Total LOS, days, mean ± SD

PT

SD

AC

Days from operation to

1.5 ± 3.5

1.3 ± 2.4

20.1

0.577

123.5 ± 119.1

57.1 ± 37.1 0.004

1.8 ± 4.3

31.1 5.4 ± 4.0

1.4 ± 3.1

0.127 5.1 ± 3.7

8 (1.8)

5.7 ± 4.4 0.080

42 (8.2)

12 (7.1)

0.610 Reoperation, n (%)

8(0.5)

1 (0.2)

0.641 22 (4.3)

0.455

0.016

6.0 ± 4.5

0.445 24 (1.4)

0.015

64.8 ±

0.123

discharge, mean ± SD Readmission, n (%)

0.391 103.4 ± 83.4

44.7 ±

value

0.191

0.245

MA

*

P

5 (3.0) 0.437

* Superficial surgical site infection, deep surgical site infection, organ/ space surgical site infection, wound disruption; LOS: Length of Hospital stay

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ACCEPTED MANUSCRIPT Table 4 Multivariable analysis for categorical outcomes overall morbidity and wound complications Outcome Overall morbidity

Wound complications

OR (CI 95%)

P

OR (CI 95%)

P

Obesity

1.25 (0.82 – 1.91)

0.29

1.28 (0.84 – 1.97)

0.24

Pulmonary risk factor

1.13 (0.52-2.46)

0.75

1.29 (0.59-2.80)

0.52

1.09 (0.31-3.89)

0.90

0.99

0.96 (0.28-3.37)

0.96

0.56

1.32 (0.36-4.90)

0.67

0.55

0.87 (0.59-1.29)

0.49

≤3≤8

1.15 (0.32-4.09)

9 ≤ 15

1.01 (0.289-3.524)

> 15

1.47 (0.4033-5.419)

NU

0.83

MA

0.89 (0.64-1.304)

ED

Race

RI P

SC

Age

Gender

T

Risk factors

1.08 (0.58-1.99)

0.81

1.15 (0.61-3.12)

0.66

Black

0.32 (0.04-2.50)

0.27

0.44 (0.59-3.23)

0.43

1.61 (0.94-2.75)

0.08

1.57 (0.91-2.70)

0.11

7.16 (4.80- 10.68)

0.000

7.52 (5.02-11.26)

0.00

1.23 (0.76-1.67)

0.56

1.11 (0.75-1.67)

0.60

0.91 (0.38-2.15)

0.82

0.78 (0.32-1.97)

0.60

9.21 (1.06-79.86)

0.04

9.11 (1.05-78.88)

0.05

PT

White

CE

Asian

ASA class I/II III IV/V

AC

Complicated appendicitis

ASA: American society of anesthesiologists;

20

AC

CE

PT

ED

MA

NU

SC

RI P

T

ACCEPTED MANUSCRIPT

Figure 1 Flowchart: Patients excluded from the analysis

21