Obesity and anti-obesity medical and surgical management

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27 Obesity and anti-obesity medical and surgical management

Case, Part 1

SB is a 48-year-old woman with type 2 diabetes mellitus, hypertension and hyperlipidemia who presents for weight loss. She reports struggling with weight since childhood but started gaining most significantly after her pregnancies, the last of which was at 28 years of age. She has tried several popular diets, including diet books and diet centres. She has also tried pills for weight loss, both ‘over the counter’ and ordered from television without success. Her current diet consists of a fast food sandwich and large diet soda in the mid-morning ‘on the run’, a piece of fruit with cheese and crackers at home in the mid-afternoon, and large meal with a meat, starch and vegetable for dinner with her family at home four nights a week and eating out the other three. In the evening, she snacks on a piece of cake, ice-cream or popcorn. She craves sweets, especially when stressed, and struggles with large portion sizes. She wants to avoid surgery if possible, but is open to hearing more about it. Her family history is significant for obesity in her mother and two of her three siblings, and hyperlipidaemia in her father and mother. She takes rosiglitazone 2 mg-metformin 1000 mg twice daily, insulin aspart 20 units with each meal, insulin glargine 45 units at bedtime, simvastatin 40 mg daily and lisinopril 20 mg twice daily. Pertinent physical exam findings include a weight of 126 kg, height of 162 cm, and body mass index (BMI) of 48.0 kg/m². She has a waist of 42 inches. Her labs are unremarkable.

Introduction

Obesity has reached epidemic proportions in the United States of America and Australia, affecting over 30% of the population. In the USA, the prevalence of obesity has increased from 22.9% in 1988 to 30.5% in 2002. This disease affects all ages, races and genders. Obese individuals suffer not only from obesity and its social stigma, but also from medical comorbidities. Over 300,000 deaths each year are attributable to obesity. For people with a BMI over 30, the relative risk of developing diabetes is 12.7 in women and 5.2 in men. The risk of death from cancer may be 40–80% higher in the heaviest men and women. These obesity-associated health problems result in repeated physician office visits, time lost from work, and escalating healthcare costs. In 2000, the economic cost of obesity was $117 billion. If the obesity epidemic continues to grow, scientists predict a decrease in life expectancy by 2050. It is clear that obesity is a significant issue for our national health.

Medical Management

Pharmacotherapy and behaviour modification are the mainstays of non-surgical treatment of obesity, with behaviour modification being the oldest approach to weight loss. Most commonly applied as a program of decreased caloric intake coupled with increased physical activity, behavioural programs have been effective in curtailing weight gain and improving overweight and moderate obesity; however, these behaviour changes and resultant weight loss are difficult for patients to sustain. Additionally, the magnitude of weight loss only modestly improves the health of patients with morbid obesity, those in the greatest need for weight management. Behaviour modification programs usually result in loss of 5–10% of body weight over a 6-month period, but this loss is rarely maintained beyond 6–12 months. High protein, low-carbohydrate diets have had some recent popularity, but a study has shown that at 1 year there was little difference in outcome when such a diet was compared with a conventional diet. Very-low-calorie diets result in more rapid weight loss, but are not a long-term solution without significant, sustained behaviour modification. The risk of malnutrition and need for frequent changes to medication make medical supervision imperative, increasing the cost and decreasing the ease of access to this type of program.

Many pharmacological therapies exist for assistance with weight loss. The two medications approved for long-term use, orlistat (which inhibits dietary fat absorption) and sibutramine (which suppresses appetite), have been shown to produce modest weight loss. However, these medications have many unwanted side effects (such as diarrhoea with orlistat) that lead to non-compliance. When patients stop taking the medication, they often regain their lost weight. Finally, these medications are expensive and a considerable burden economically. Whether behaviour modification, pharmacotherapy or a combination of these approaches, the bottom-line issue with non-surgical weight management remains failure to achieve clinically significant weight loss for morbidly obese patients and failure to sustain weight loss for most patients. For many obese individuals, continued pursuit of these programs leads to recidivism, incremental weight gain, and the negative psychological and physiological consequences of repeated failures.

Recently, there has been interest in several putative gut hormones and their role in appetite, glucose metabolism and overall metabolism. Levels of glucagon-like peptide 1 (GLP-1), peptide YY (PYY), ghrelin, cholecystokinin (CCK), gastric inhibitory peptide (GIP), oxyntomodulin (OXW) and pancreatic polypeptide have all been shown to have anorexigenic or orexigenic effects, and some degree of change after various weight loss operations. This has renewed interest in the gut–brain axis and the regulating peptides, and their potential role in future weight management strategies.

Case, Part 2

SB is provided with information about both non-surgical and surgical options. She elects to pursue a non-surgical treatment regimen. She is placed on a 1200 calorie American Diabetes Association diet, which includes a regular eating schedule. Her dietitian also assists her with meal planning and preparation improvements. She increases her activity to incorporate 3 or 4 days per week of 30–60 minutes of aerobic exercise and on the other days uses a pedometer to accumulate an increasing number of steps. She works with a clinical health psychologist to improve her stress management, decrease her eating out and manage her cravings. Over a 6-month period, she is able to reduce her weight by 11% to 112 kg, yielding a BMI of 42.7. She has discontinued her rosiglitazone and decreased her insulin aspart to 15 units with meals, insulin glargine to 30 units at bedtime and lisinopril to 20 mg daily. However, she continues to require her metformin 1000 mg twice daily and simvastatin 40 mg at bedtime. After maintaining her weight within 2.27 kg for another 6 months, she decides to pursue gastric bypass surgery for additional weight loss and improvement of her diabetes.

Surgical Management

The rapid increase in the prevalence and morbid consequences of obesity combined with failure of those weight-loss strategies outlined earlier has led to increased interest in surgical management of obesity. Various operations to induce weight loss have been available and used for nearly 40 years. The epidemic of obesity combined with the use of laparoscopy in performing weight-loss operations has led to a dramatic rise in the number of procedures performed. It is estimated that in 2004 140,000 morbidly obese individuals underwent weight-loss surgery, an increase of over 300% when compared with the 40,000 similar procedures performed in 1999. Today, three procedures are most commonly offered: the roux-en-Y gastric bypass (GBP), the laparoscopic adjustable gastric band (LGB) and the sleeve gastrectomy, with the roux-en-Y gastric bypass remaining the most commonly performed weight-loss operation. The vertical gastric band (VBG) is now largely of historic interest since up to 25% of patients require revisional surgery after this operation, and durable weight loss is insufficient when compared to the other procedures. The biliopancreatic bypass with duodenal switch (BPO-DS) continues to have limited use in select patients at select centres.

Roux-en-Y gastric bypass

The Roux-en-Y gastric bypass (GBP) (Fig 27.1) is the most commonly performed procedure in the United States of America and works in three ways. A small pouch of 30-mL volume is created along the lesser curve of the stomach, resulting in restriction to food intake. A 100- to 150-cm Roux limb drains this proximal gastric pouch, resulting in malabsorption. Finally, because ingested food bypasses the main portion of the stomach, certain foods (e.g. sweets) induce the dumping syndrome, which limits patients’ consumption of these foods. After a GBP, 90% of patients lose 50–75% of their excess weight, and this loss is maintained for at least 14 years.

Figure 27.1 Anatomy of Roux-en-Y gastric bypass.

Laparoscopic adjustable gastric band

The laparoscopic adjustable gastric band (LGB) (Fig 27.2) procedure places an adjustable Silastic™ band around the gastric cardia, thereby creating a small proximal gastric pouch with a restricted outlet to the distal stomach. The LGB has essentially replaced the vertical banded gastroplasty as an effective restrictive-only procedure. While the GBP remains the most commonly performed procedure in the USA, the LGB is the most commonly performed weight-loss procedure in the world. Five-year outcomes reveal that most patients lose 50% to 60% of their excess weight.

Figure 27.2 Anatomy of laparoscopic adjustable gastric band.

Sleeve gastrectomy

Sleeve gastrectomy (Fig 27.3) has recently become an increasingly common and popular operation. This procedure developed as part of the duodenal switch operation and was used as a staging procedure for extremely obese or high-risk patients. These patients would undergo an initial operation consisting of the sleeve gastrectomy only with the plan to later undergo another surgery to complete the duodenal switch. Weight loss with sleeve gastrectomy only induced sufficient and durable weight loss, making the sleeve gastrectomy alone a reasonable operation. This operation achieves 50–75% excess weight loss without the perioperative risks of the more complex anatomic reconstruction of the GBP.

Figure 27.3 Anatomy of sleeve gastrectomy.

Outcomes of surgery

Minimally invasive techniques have been used for weight-loss surgery since the first laparoscopic GBP was performed in 1994. Since that time laparoscopic techniques have increasingly dominated weight-loss surgery, with patients realising the expected results regardless of the method of access (open or laparoscopic). These overall results include sustained weight loss with either improvement or complete resolution of comorbidities after surgery. In a recent systematic review of the literature, 22,094 patients were included and the results were as follows: the mean percentage weight loss was 61.2% for all patients, with the most excess weight loss observed with GBP (68.2%). Diabetes resolved in 76.8% of patients, hypertension in 61.7% of patients, and obstructive sleep apnoea in 85.7% of patients.

Furthermore, an economic advantage with surgical weight loss has been suggested (see pros and cons below). One study demonstrated that with the resolution of many of these comorbidities the cost per patient of pharmaceuticals after weight-loss surgery was significantly decreased. Furthermore, a recent study has demonstrated that patients who underwent weight-loss surgery experienced lower mortality than those who remained obese. Obesity has been identified as the second most common cause of preventable death in the United States of America. This elevated death rate will revert back to that of the normal population with return to a non-obese weight. Another area of impact has been cancer; obesity may account for 14% of cancer deaths in men and 20% in women. With weight loss, one in six cancer deaths may be prevented in the United States.

Pros and Cons of Weight-loss Surgery

With such positive outcomes from weight-loss surgery, the question could be asked: why hasn’t everyone with morbid obesity undergone weight-loss surgery? Currently, over 16 million Americans are potential candidates for weight-loss surgery (BMI over 40 or BMI over 35 with comorbidities). At the rate of just over 140,000 procedures being performed in 2004, it will take at least 150 years to address the current population. Several factors limit the number of weight-loss operations performed.

First, there are not enough surgeons who perform weight-loss surgery to operate on all of these people even within the next decade. Also, weight-loss surgery is not appropriate for all obese individuals. Several surgical and non-surgical factors influence the outcome after weight-loss surgery. For example. weight regain at 18–24 months after surgery is noted in up to 30% of patients. One factor identified in weight regain is binge-eating disorder. Patients with a history of binge-eating behaviour frequently revert to their old habits after surgery, and this could explain weight regain in some patients. In contrast, patients with the most success after weight-loss surgery have an overall improved eating behaviour and also have greater physical activity. For success with surgery, patients need to be willing to accept these lifestyle changes and be able to modify their eating habits in accordance with the surgery. Not all patients are willing to comply with such changes, and therefore not all patients are proper candidates for surgery.

Many of the patients seeking weight-loss surgery are young and have a life expectancy of at least 30 years after their weight-loss procedure. We do not know the long-term (over 20 years) effects of the gastrointestinal anatomic alterations of current weight-loss procedures. We do know that 7–29% of patients will require cholecystectomy after any weight-loss surgery, and 10–15% of LGB patients will require more surgery for band erosion, leakage or slip. There are also concerns about long-term nutritional and micronutrient deficiencies, especially with the GBP where a significant portion of the GI tract has been bypassed. Patients who undergo this malabsorptive procedure must be monitored for life, in particular for iron, vitamin B₁₂ and calcium deficiencies. Vitamin B₁₂ and calcium supplementation is indicated lifelong in all GBP patients, and foods rich in protein can be a challenge, thereby often necessitating protein supplementation.

Case, Conclusion

SB undergoes gastric bypass after preparation by her bariatric team, incorporating appropriate dietary changes and supplementation. Over her first year she meets with her dietician and physician regularly and continues her aerobic exercise while adding resistance exercise. She is able to reduce her weight to 79 kg, yielding a BMI of 30.1. Her lisinopril, insulin aspart and insulin glargine metformin are discontinued, but she continues with simvastatin 20 mg at bedtime to control her persistent hyperlipidaemia. After the first year, she meets with the team annually for monitoring. With continued vigilance, she is able to maintain her weight loss with a significant improvement in her health and quality of life.

Conclusions

Obesity remains a significant health concern. Weight-loss surgery is the most sustainable weight-loss option for the majority of morbidly obese adults. As long as the person is motivated to make the lifestyle changes required by the various weight-loss options, he or she can enjoy the benefits of fewer comorbidities, fewer medications, fewer costs and an improved quality of life. In the long term, however, surgery will not be the answer. Not enough surgeons are available to address the current obese adult population, and the prevalence of obesity continues to rise. Education and public awareness are the long-term solution to decrease the incidence of obesity and prevent children from becoming obese adults. It has taken several decades for obesity to reach its current epidemic proportions. It will take many more to get the population back to a healthier weight.

Key Points

• Most non-surgical obesity treatments can produce a weight loss of 5–10% over 6 months.

• A weight loss of 5–10% will improve health, but usually not enough for patients with morbid obesity.

• Sibutramine (an anorexiant) and orlistat (an intestinal lipase inhibitor) are the only medications currently approved for long-term use for the treatment of obesity. Note that the US Food and Drug Administration (FDA), as of 8 October 2010, has recommended against continued prescribing of sibutramine: see http://www.fda.gov/Drugs/Drugsafety/ucm228746.htm#Safety_Announcement

• Surgical treatment produces greater weight loss that is sustained over a longer period of time than non-surgical treatments.

• Gastric bypass produces more weight loss than gastric banding and may be comparable to sleeve gastrectomy.

• Gastric bypass resolves up to 80% of type 2 diabetes mellitus.

• Those who undergo a malabsorptive procedure must be closely monitored for nutritional deficiencies for life (e.g. B₁₂, calcium).

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