Surgical Implications of Pediatric Obesity
Michael A. Helmrath
Thomas H. Inge
Mary L. Brandt
Victor Garcia
Baylor College of Medicine, Texas Children’s Hospital Care Center, Houston, Texas 77030.
Comprehensive Weight Management Center Division of Pediatric General and Thoracic Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio 45229.
Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030.
University of Cincinnati, Cincinnati, Ohio 45267.
Obesity is now considered the most common nutritional disorder of children and adolescents in the United States, with 15% of children and adolescents classified as overweight and almost 30% either overweight or at risk of being overweight (1,2). No longer a disease limited to adults, pediatric specialists are now confronted with a new set of diagnostic and therapeutic dilemmas in overweight and obese children and adolescents (2,3,4,5,6). Direct and indirect costs attributed to obesity in the United States have been estimated to approach $75 to $100 billion per year (7,8). Twenty-five percent to 83% of obese children become obese adults, suggesting that early intervention will be not only effective, but also essential. Numerous studies have shown that obesity in childhood is associated with increased morbidity and mortality, both in childhood and in adulthood (3,5,9,10,11). Being morbidly obese at age 20 is associated with a predicted 13-year reduction in life span for white males, and a 20-year reduction in life span for African American males (11). In a 55-year follow-up of school children in Boston, Must et al. demonstrated a twofold increase in death from all causes in boys who had been overweight [body mass index (BMI) > 75th percentile] in adolescence (9). The risk of dying from atherosclerotic disease was increased 2.3-fold, from cerebrovascular disease 13.2-fold, and from colon cancer 9.1-fold (9). This increased mortality risk was not seen in the girls followed in this study (9). However, the girls did have an eight times higher risk of difficulty with personal care and activities of daily living as adults, when compared with the lean control group and a 1.6 times increased risk of arthritis (9). Childhood obesity also affects physical and psychological growth and development, a consequence that cannot be quantified in a monetary sense, but is perhaps the most significant “cost” this disorder inflicts on these children (5,12,13). Obese children are more at risk for poor self-esteem, withdrawal from social interactions, depression, and anxiety (2). Obese adolescents are more likely to remain unmarried, have lower incomes, and live in poverty than their matched normal weight controls (14). They are less likely to be accepted into college than normal weight adolescents with comparable scholastic achievement (5). In a more recent study, the health-related quality of life experienced by obese children and adolescents was the same as that of children undergoing chemotherapy for cancer (15).
All children seen in a health care setting should have a height and weight obtained, with percentiles based on growth charts recorded. In addition, these two measurements allow easy calculation of the BMI, which is weight (kg) per height (m)2. BMI changes with age; the 50th percentile for male BMI at 6, 12, and 18 years of age is 15.4 kg per m2, 18 kg per m2, and 22 kg per m2, respectively. BMI values recorded on BMI growth charts [available on the Centers for Disease Control and Prevention (CDC) web site, http://www.cdc.gov] allow tracking of percentile changes over time to identify children at risk for obesity. One of the problems in interpreting the literature on obesity in children is the different ways obesity has been defined in the pediatric population. Growing children have been classified as normal (BMI < 85th percentile), at risk for overweight (BMI 85th to 95th percentile), or overweight (BMI > 95th percentile) (13). In adolescents, who have completed linear growth, it may be more appropriate to use adult criteria: A BMI of greater than 25 is considered overweight and a BMI greater than 30 obese. Obese adolescents can further be classified using the criteria defined by the National Institutes of Health (NIH): class 1 obesity (BMI 30–34.9), class 2 obesity (35–39.9), and class 3 or “morbid”
obesity (BMI greater than 40). Finally, in the surgical literature, patients with a BMI greater than 50 have been termed “super obese.” The patient’s BMI and the medical issues associated with obesity should be discussed at every clinic visit with the child and family. In this way, appropriate interventions and/or referrals can be initiated (2,16). The medical and psychosocial rather than cosmetic implications of obesity should be discussed. It should be stressed that weight management efforts that result in a loss of 5% to 10% of body weight can result in a significant reduction of obesity-related health risks (17).
obesity (BMI greater than 40). Finally, in the surgical literature, patients with a BMI greater than 50 have been termed “super obese.” The patient’s BMI and the medical issues associated with obesity should be discussed at every clinic visit with the child and family. In this way, appropriate interventions and/or referrals can be initiated (2,16). The medical and psychosocial rather than cosmetic implications of obesity should be discussed. It should be stressed that weight management efforts that result in a loss of 5% to 10% of body weight can result in a significant reduction of obesity-related health risks (17).
COMORBIDITIES OF OBESITY
Obesity can cause or contribute to the development of numerous comorbidities (Table 73-1). These comorbid conditions may be silent, and it is incumbent upon the pediatric surgeon to screen for these disorders prior to planning any elective surgery in obese children. In addition, the presence of one or more of these major comorbid states in a child mandates aggressive intervention to treat the underlying obesity.
Cardiac risk factors are common in obese children and include insulin resistance, hyperlipidemia, sleep apnea, and hypertension. Fifty percent of overweight adolescents have one risk factor for developing cardiovascular disease and 20% have two factors (3). Hyperlipidemia in obese children is most often manifested by elevated low-density lipoprotein-cholesterol, elevated triglycerides, and decreased high-density lipoprotein-cholesterol (12). Twenty percent to 30% of obese children between ages 5 and 11 have elevated systolic or diastolic blood pressure (5). Clinical hypertension is 9 to 10 times more common in obese children than in lean children (12,18). Significant, irreversible consequences of hypertension, such as hypertensive cardiac disease, can present in childhood. In one study, 38% of children with
hypertension had left ventricular hypertrophy by echocardiography (18). More important, nearly 30% of obese adolescents have already developed the metabolic syndrome (syndrome X; the clustering of abdominal obesity, high fasting blood glucose, hypertension, and hyperlipidemia). This dangerous condition may have profound public health implications given the fact that up to 910,000 adolescents in the United States may be affected based on current population trends (19).
hypertension had left ventricular hypertrophy by echocardiography (18). More important, nearly 30% of obese adolescents have already developed the metabolic syndrome (syndrome X; the clustering of abdominal obesity, high fasting blood glucose, hypertension, and hyperlipidemia). This dangerous condition may have profound public health implications given the fact that up to 910,000 adolescents in the United States may be affected based on current population trends (19).
TABLE 73-1 Comorbidities of Obesity. | |
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Glucose metabolism and insulin sensitivity are altered by obesity (20). There has been a dramatic increase in the prevalence of type II diabetes in the pediatric population, and this is primarily the result of the increased prevalence of obesity (20,21). The ramifications of the obesity epidemic are major and worrisome. Current projections by the CDC include scenarios in which up to one-third of the children born today will develop type 2 diabetes mellitus during their lifetime, a percentage that rises to one-half for Hispanics and blacks (22). Because type 2 diabetes is often asymptomatic in the early stages, obese children undergoing surgery may benefit from a screening fasting blood glucose. Acanthosis nigrans, or increased thickness and pigmentation of skin in the intertriginous folds, is associated with hyperinsulinemia (12). The presence of acanthosis nigrans, most commonly diagnosed by examining the back of the neck, may indicate the need for formal glucose tolerance testing by a pediatric endocrinologist. The history of vaginal yeast infections in an obese adolescent should also prompt further workup for diabetes (20).
Sleep disorders are extremely common with childhood obesity. Up to 37% of obese children have an abnormal polysomnogram when studied (10,23). Most of these abnormalities are minor, with true sleep apnea occurring in only 7% of obese children (12). Symptoms of sleep apnea may include snoring, poor school performance, daytime sleepiness, enuresis, and hyperactivity (10). However, there is no clear correlation between symptoms and the severity of the sleep apnea, making this difficult to diagnose (12). Weight loss results in improvement of sleep apnea. In addition, many of these children demonstrate clinical improvement with tonsillectomy and/or adenoidectomy, suggesting that many of these patients would benefit from otorhinolaryngologic examination (23,24,25). Obesity hypoventilation syndrome, previously called Pickwickian syndrome, is an extreme version of sleep apnea and can result in hypoxia, hypercarbia, right ventricular hypertrophy or failure, and polycythemia (10).
Blount’s disease (tibia vara) is defined as overgrowth of the medial aspect of the proximal tibial metaphysis, which occurs in response to and then accentuates “bowing” of the legs under the pressure of excess weight (12). Sixty-six percent to 80% of patients with Blount’s disease are obese (5,12). Obesity in childhood may also result in slipped capital femoral epiphyses (12). Fifty to 70% of children with slipped capital femoral epiphyses are obese, and severe obesity complicates the orthopedic management of this deformity (5).
Polycystic ovarian syndrome, previously called Stein-Leventhal syndrome, is the most common endocrinopathy in women (26). It is a complex metabolic disease that may present in adolescents and is associated with obesity (12). This syndrome is manifested by oligomenorrhea or amenorrhea associated with obesity, insulin resistance, hirsutism, acne, and acanthosis nigricans (5). Ultrasound of the ovaries, particularly in adolescent girls, is often normal, with no evidence of pathologic ovarian cysts. Patients with suspected polycystic ovarian syndrome should be evaluated by a pediatric endocrinologist.
Nonalcoholic fatty liver disease (NAFLD) is one of the silent, but potentially dangerous comorbidities of obesity in childhood (27). NAFLD is a spectrum of disease ranging from fatty infiltration of the liver to steatohepatitis (termed NASH for nonalcoholic steatosis/hepatitis) to fibrosis and cirrhosis (28). Up to 40% of obese children have findings on ultrasound suggestive of fatty infiltration of the liver (10). Approximately 10% of obese children and 40% to 50% of severely obese children have abnormal liver function tests and this is frequently, but not always, associated with NAFLD (5,12,13). Serum liver enzyme levels can be used as a screening test, but the definitive diagnosis is made by liver biopsy. Liver biopsy should be considered in any obese child with abnormal liver function tests or ultrasound, or visible changes in the parenchyma of the liver. Up to 20% of adult patients with this disorder eventually develop cirrhosis, and this may progress to liver failure (27). NAFLD is almost universally associated with insulin resistance and, therefore, appropriate testing should be done in children with this diagnosis to screen for this disorder (28). Weight loss is the only known treatment for NAFLD (12,27).
Biliary disease is also common in obese children. Fifty percent of adolescent patients undergoing cholecystectomy for cholelithiasis are obese (13). Eight percent to 33% of all gallstones seen in childhood are related to obesity (5).
Pseudotumor cerebri is a rare disorder characterized by a gradual and idiopathic increase in intracranial pressure (12). The usual presentation is headaches, but patients may also experience dizziness, unsteadiness, or diplopia (10,12). Approximately 50% of children with pseudotumor cerebri are obese (12). There is no effective therapy other than weight loss. If untreated, this syndrome may result in visual impairment, need for optic nerve fenestration, or even blindness (12).
MEDICAL TREATMENT OF OBESITY
The mainstay of medical therapy for obesity is dietary and behavioral change (29,30,31). The abundance and variety of diet books and programs available in our society is reflective of how ineffective most of these strategies are for adults. It is not surprising that 90% to 95% of adult patients who lose weight with dietary changes alone regain the weight (29). One pound of fat (0.45 kg) is the equivalent of 3,500 kcal of energy. Thus, to lose 1 lb of excess weight, an overall change of 3,500 kcal must be made from the patient’s baseline. As an example, a change of 500 kcal per day for a week will result in a loss of 1 lb of body weight. This can be accomplished by reducing daily intake by 500 kcal, increasing daily caloric expenditure (exercise) by 500 kcal, or a combination. Education concerning the relationship between food intake, caloric expenditure, and weight gain can result in effective weight control in some patients. However, most patients require more intensive diet control and behavioral modification for success, which is limited even in the most intensive programs. Physician-controlled diets, such as the protein-sparing modified diet or ketogenic diet, may have some utility in the treatment of severely obese adolescents, but the long-term effects and outcomes in the pediatric population are not known (31).
Pharmacologic interventions for weight control have been used with limited success in adult patients and are not recommended currently for routine use in children (32). Two drugs are in clinical trials but are not approved currently for use in children and adolescents: sibutramine, a serotonin-mediated appetite suppressant, and orlistat, which inhibits fat absorption (31). A more recent randomized controlled study of sibutramine in severely obese adolescents (mean BMI 37 kg per m2) demonstrated an average 10% weight loss, with a side effect profile requiring dose reduction or medication cessation in 33 of 88 (37%) patients (33). Further clinical trials of these two drugs will be needed before treatment recommendations can be made.
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