Impact of Body Mass Index on 30-day Postoperative Morbidity in Pediatric and Adolescent Patients Undergoing Continent Urinary Tract Reconstruction - Beyond the Abstract

Childhood obesity has become an epidemic with a wide variety of consequences in public health. Its prevalence has significantly increased over the past 40 years and is currently 18.5% in children and adolescents between 2-19 years of age in the United States in 2015-2016.1 The association between obesity and surgical outcomes has become an area of interest with the recent initiatives to improve the quality and reduce the cost of surgical care. Obesity has been thought to increase the risk of complications and the need for additional resources due to the increased technical difficulty with surgery and frequent comorbid conditions.


The objectives of our study were to describe the weight status of 182 pediatric and adolescent patients up to 20 years of age undergoing a lower urinary tract reconstruction and to determine the association between obesity and 30-day postoperative morbidity. Our cohort had a relatively low proportion of patients with myelomeningocele at 36.3%, with a majority of the remaining patients having an anorectal malformation or exstrophy. Weight status was stratified by body mass index (BMI) for age z-scores as follows: underweight (<5th percentile), normal (5th to <85th percentiles), overweight (85th to <95th percentiles), and obese (≥95th percentile). The effect of BMI was analyzed by comparing the four groups of weight status as well as comparing the non-overweight or non-obese group (BMI for age z-score ≥85th percentile) and overweight or obese group (BMI for age z-score ≥85th percentile). No demographic or perioperative data differed by weight status, including the type of continent catheterizable channel(s) and the need for augmentation enterocystoplasty and other additional procedures. Obesity, as determined by BMI, was not associated with the length of intensive care, length of hospitalization, 30-day complications, or 30-day readmissions. There was also no association in a subgroup analysis between patients with and without myelomeningocele as well as for infectious, wound, or high-grade complications.

Obesity has been consistently associated with an increased risk of surgical site infections (SSIs) and wound complications after a wide variety of surgeries in adults. Similar findings were reported in 2 recent studies using the pediatric NSQIP database for children undergoing surgery by all subspecialties and those only undergoing urologic surgery.2,3 Lower urinary tract reconstruction is among the most complex and morbid surgeries in pediatric urology with high rates of complications and readmissions. The risk of SSIs and wound complications is particularly high due to the potential for fecal spillage and a longer duration of surgery. Only one study has focused on patients undergoing a lower urinary tract reconstruction, which demonstrated an increased risk of complications with a rate of 75% in obese patients and 40% in both normal and overweight patients. This cohort was much older with the inclusion of adults and only included those with myelomeningocele. Furthermore, the authors did not use a standardized system for the classification of complications and arbitrarily defined the perioperative period.4 Many in our cohort underwent an augmentation enterocystoplasty and/or had a bowel anastomosis. The operative times were also long, particularly in patients with multiple prior abdominal surgeries and anorectal malformations that required a multidisciplinary involvement of colorectal surgery and/or gynecology. The high-risk nature of our cohort may have mitigated any effect of obesity on 30-day morbidity.

Our study is limited by its retrospective design at a single center, despite having a large cohort of pediatric and adolescent patients undergoing a lower urinary tract reconstruction. The misclassification of weight status in patients with myelomeningocele may also have led to bias, as BMI may not provide a reliable indicator of body composition in this population. Other measurements such as BMI by arm span, abdominal girth, and percent fat on dual-energy X-ray absorptiometry are becoming increasingly available. However, BMI remains the most readily available, least invasive, and cost-effective measurement for stratification of weight status.

Written by: Andrew C. Strine, MD, Co-Director, Comprehensive Fertility Care and Preservation Program, Assistant Professor, UC Department of Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio

References:

  1. Hales, Craig M., Margaret D. Carroll, Cheryl D. Fryar, and Cynthia L. Ogden. "Prevalence of obesity among adults and youth: United States, 2015–2016." (2017).
  2. Stey, Anne M., R. Lawrence Moss, Kari Kraemer, Mark E. Cohen, Clifford Y. Ko, and Bruce Lee Hall. "The importance of extreme weight percentile in postoperative morbidity in children." Journal of the American College of Surgeons 218, no. 5 (2014): 988-996.
  3. Kurtz, Michael P., Erin R. McNamara, Anthony J. Schaeffer, Tanya Logvinenko, and Caleb P. Nelson. "Association of BMI and pediatric urologic postoperative events: results from pediatric NSQIP." Journal of pediatric urology 11, no. 4 (2015): 224-e1.
  4. Donovan, Ben O., Mirian Boci, Bradley P. Kropp, Brianna C. Bright, Christopher C. Roth, Stephen D. Confer, and Dominic Frimberger. "Body mass index as a predictive value for complications associated with reconstructive surgery in patients with myelodysplasia." The Journal of urology 181, no. 5 (2009): 2272-2276.
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