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
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
The Impact of Obesity on Laparoscopic Appendectomy: Results from the ACS National Surgical
T
Quality Improvement Program Pediatric Database.
RI P
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,
NU
1
SC
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
MA
2
ED
Address Correspondence to: Fizan Abdullah, MD, PhD
PT
Johns Hopkins University School of Medicine
AC
Baltimore, MD 21287
CE
Bloomberg Children’s Center, Suite 7337
e-mail: [email protected] Tel (410) 955-1983 Fax (410) 502-5314
1
ACCEPTED MANUSCRIPT Abstract Background
RI P
T
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
SC
of this study was to examine the effects of obesity on surgical outcomes in children using laparoscopic
NU
appendectomy as a model for the broader field of laparoscopic surgery.
MA
Study Design
Using the Pediatric National Surgical Quality Improvement Program (NSQIP) data from 2012, patients
ED
aged 2-18 years old with acute uncomplicated and complicated appendicitis who underwent laparoscopic
PT
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
CE
complications, were compared between non-obese and obese children. Multivariate regression analysis
Results
AC
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
2
ACCEPTED MANUSCRIPT appendectomy. Although operative times are increased in obese children, obesity does not increase the likelihood of 30-day postoperative complications.
AC
CE
PT
ED
MA
NU
SC
RI P
T
Keywords: NSQIP; Pediatric; Obesity; Laparoscopic appendectomy; Outcomes
3
ACCEPTED MANUSCRIPT Introduction1 The incidence of childhood obesity has increased dramatically over the past two decades. Data
T
from the National Health and Nutrition Examination Survey showed that in the year 2012, more than one
RI P
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
SC
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.
NU
Obesity is associated with numerous potential comorbidities, including respiratory disorders,
MA
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].
ED
This may influence the post-operative immune response and account for some of the adverse post-surgical
PT
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].
CE
The knowledge of procedure-specific risk associated with obesity is important for the establishment of outcome standards that accurately reflect expected results.
AC
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
4
ACCEPTED MANUSCRIPT Surgical Quality Improvement Program (NSQIP-Pediatric). We hypothesized that obesity would
T
contribute to an increase in overall morbidity and, in particular, infectious complications.
RI P
1. Materials and Methods 1.1. Data source and study population
SC
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
NU
2012 to December 31st 2012. The population consisted of patients aged 2 to 18 years who underwent
MA
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.
ED
Cases coded as 540 (acute appendicitis) and 540.9 (acute appendicitis without peritonitis) were
PT
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
CE
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
AC
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.
5
ACCEPTED MANUSCRIPT 1.2. Outcome variables The primary outcomes of interest were 30-day mortality and overall morbidity. This composite
T
variable was defined as having at least one of the following complications: superficial, deep or organ
RI P
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
SC
intracranial hemorrhage, seizure disorder, cardiac arrest, transfusion, venous thromboembolism, sepsis, and central line associated blood stream infection.
NU
Secondary outcomes of interest included wound complication, operative time, anesthesia time
MA
(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
ED
wound occurrences: superficial, deep or organ space SSI, or wound disruption. Patients were excluded for
PT
experiencing a complication if the condition was documented preoperatively (e.g. pneumonia present
CE
preoperatively).
1.3. Statistical analysis
AC
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
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
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
The Impact of Obesity on Laparoscopic Appendectomy: Results from the ACS National Surgical
T
Quality Improvement Program Pediatric Database.
RI P
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,
NU
1
SC
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
MA
2
ED
Address Correspondence to: Fizan Abdullah, MD, PhD
PT
Johns Hopkins University School of Medicine
AC
Baltimore, MD 21287
CE
Bloomberg Children’s Center, Suite 7337
e-mail: [email protected] Tel (410) 955-1983 Fax (410) 502-5314
1
ACCEPTED MANUSCRIPT Abstract Background
RI P
T
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
SC
of this study was to examine the effects of obesity on surgical outcomes in children using laparoscopic
NU
appendectomy as a model for the broader field of laparoscopic surgery.
MA
Study Design
Using the Pediatric National Surgical Quality Improvement Program (NSQIP) data from 2012, patients
ED
aged 2-18 years old with acute uncomplicated and complicated appendicitis who underwent laparoscopic
PT
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
CE
complications, were compared between non-obese and obese children. Multivariate regression analysis
Results
AC
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
2
ACCEPTED MANUSCRIPT appendectomy. Although operative times are increased in obese children, obesity does not increase the likelihood of 30-day postoperative complications.
AC
CE
PT
ED
MA
NU
SC
RI P
T
Keywords: NSQIP; Pediatric; Obesity; Laparoscopic appendectomy; Outcomes
3
ACCEPTED MANUSCRIPT Introduction1 The incidence of childhood obesity has increased dramatically over the past two decades. Data
T
from the National Health and Nutrition Examination Survey showed that in the year 2012, more than one
RI P
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
SC
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.
NU
Obesity is associated with numerous potential comorbidities, including respiratory disorders,
MA
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].
ED
This may influence the post-operative immune response and account for some of the adverse post-surgical
PT
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].
CE
The knowledge of procedure-specific risk associated with obesity is important for the establishment of outcome standards that accurately reflect expected results.
AC
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
4
ACCEPTED MANUSCRIPT Surgical Quality Improvement Program (NSQIP-Pediatric). We hypothesized that obesity would
T
contribute to an increase in overall morbidity and, in particular, infectious complications.
RI P
1. Materials and Methods 1.1. Data source and study population
SC
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
NU
2012 to December 31st 2012. The population consisted of patients aged 2 to 18 years who underwent
MA
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.
ED
Cases coded as 540 (acute appendicitis) and 540.9 (acute appendicitis without peritonitis) were
PT
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
CE
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
AC
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.
5
ACCEPTED MANUSCRIPT 1.2. Outcome variables The primary outcomes of interest were 30-day mortality and overall morbidity. This composite
T
variable was defined as having at least one of the following complications: superficial, deep or organ
RI P
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
SC
intracranial hemorrhage, seizure disorder, cardiac arrest, transfusion, venous thromboembolism, sepsis, and central line associated blood stream infection.
NU
Secondary outcomes of interest included wound complication, operative time, anesthesia time
MA
(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
ED
wound occurrences: superficial, deep or organ space SSI, or wound disruption. Patients were excluded for
PT
experiencing a complication if the condition was documented preoperatively (e.g. pneumonia present
CE
preoperatively).
1.3. Statistical analysis
AC
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
