The last National Health Survey in 2010 found that 11% of Singaporean adults aged between 18 and 69 were obese, up from 7% in 2004. Assuming another 5% increment from 2010 to 2016, this would have amounted to a staggering total of half a million people living with obesity in Singapore today.

In 2007, as a surgical resident at Hopkins assigned to a bariatric surgical rotation, one would typically see 3 to 4 gastric bypass operations a day. That would give a rough estimate of 20 cases a week, and in a month – 80 cases!

The World Health Organization (WHO) indicates that there are over 1.9 billion overweight adults in 2014 alone. There are approximately 2.8 million obesity-related deaths each year.

In 2013, the American Medical Association recognised obesity as a disease. The decision was to improve access to weight loss treatment, reduce the stigma of obesity and underscore the fact that obesity is not always a matter of self-control.

Obesity is a significant risk factor for death. A myriad of studies have demonstrated an inverse relationship between BMI (body mass index) and lifespan. Studies from the National Institutes of Health found extreme obesity to shorten life expectancy by 14 years. Obesity not only affects lifespan, but in itself is a signficant burden on the quality of life of each afflicted person and their families.

Obese patients often have a multitude of associated medical conditions e.g.:

• Lymphoedema
• Osteoarthritis
• Chronic back pain
• Gastro-oesophageal reflux disease
• Urinary stress incontinence
• Sleep apnoea
• Metabolic/endocrine conditions such as diabetes mellitus, high cholesterol, fatty liver, gallstones
• Infertility
• Irregular menses
• Cancers like breast, stomach, pancreas, uterine, prostate and colon
• Cardiovascular diseases like hypertension, coronary heart disease, congestive heart failure
• Deep venous thrombosis
• Stroke
• Psychologically, obese patients tend to experience a higher incidence of depression and anxiety. They are often the object of social isolation and discrimination.

At a fundamental level, obesity occurs when people eat more calories than they would normally burn. Eating behaviour in itself is complex and is driven by the combined actions of genes, hormones and neural circuits. To think that it is purely a function of willpower is oversimplistic. Promotion of lifestyle change i.e. eating less calories and increasing physical activity, has notoriously high recidivism rates and inter-individual variability.

Many studies have shown that surgery leads to significantly greater and more sustained weight loss than lifestyle modifications. Coincidentally, surgery also demonstrated higher remission rates of type 2 diabetes and metabolic syndrome. As a result, these patients demonstrate better performances on quality of life studies compared to non-surgical patients.

MANAGEMENT

On a practical level, bariatric patients are tricky to manage. Weight alone poses a significant challenge for the patient, physicians and allied health professionals. In the US, bariatric patients can weigh anywhere between 200-300 kg. Most of them require assistance to go from point A to point B. Often, they are wheelchair- or bed-bound. Transferring such patients often require the help of 6-7 staff. Customised hospital beds and armchairs have to be created for their use whilst in hospital. But with surgery, after only 6-12 months, many patients walk into the clinic unaided.

Currently, the two commonest procedures in Singapore are Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy. Both types of bariatric procedures have demonstrated excellent long-term weight loss. Surgery is performed via small incisions in the abdominal wall ranging from 0.5-1.5 cm with the help of a small camera (laparoscopic surgery).

After surgery, our patients stay overnight for observations and are usually fully recovered in 3-4 weeks. On average, patients will lose 25-30% of their initial body weight within 6-12 months (Figures 1 & 2).

The technical aspects for each surgery are as follows:

Roux-en-Y Gastric Bypass (RYGB)
1. On one hand, for RYGB, a small stomach pouch, approximately 30 millilitres in volume, is created by dividing the top of the stomach from the rest of the stomach.

2. Next, the first portion of the small intestine is divided, and the bottom end of the divided small intestine is brought up and connected to the newly-created small stomach pouch.

3. The procedure is completed by connecting the top portion of the divided small intestine to the small intestine further down so that the stomach acids and digestive enzymes from the bypassed stomach and first portion of small intestine (duodenum) will eventually mix with the food (Figure 3).

The gastric bypass works by several mechanisms. Firstly, the newly-created stomach pouch is considerably smaller and therefore the patient experiences early satiety, translating into fewer calories consumed per meal. Secondly, due to the exclusion of a length of proximal small intestines, only a percentage of the ingested volume of food is absorbed, further reducing the amount of effective calories the body uses.

In addition to the physical barrier provided by surgery in preventing calories from being absorbed, at a cellular level, re-routing the gut produces changes in gut hormones that promote satiety, suppresses hunger, and reverses one of the primary mechanisms by which obesity induces type 2 diabetes.

Therefore RYGB not only produces excellent weight loss but also results in improvement of blood sugar and causes a reversal in metabolic syndrome (average of 32% baseline weight loss, 62% remission of dyslipidaemia and 38% remission of hypertension).

In the literature, Schauer et al. from Cleveland¹, Ikramuddin et al. from Minnesota² and Mingrone et al. from Rome³ demonstrated superior remission rates of uncontrolled diabetes in obese patients undergoing RYGB, vertical sleeve gastrectomy (VSG) or bilio-pancreatic diversion compared to intensive medical therapy alone in prospective randomised trials.

The Swedish Obesity Subjects study⁴ and Adams et al.⁵ similarly demonstrated superior long-term (18 years and 15 years respectively) resolution of obesity-related comorbidities in patients who underwent RYGB versus non-surgical interventions.

Vertical Sleeve Gastrectomy (VSG)
VSG on the other hand, is the commonest weight loss procedure performed in Singapore due to its high weight loss and low risk of surgery profile.^6-8

Advantages of VSG include:
1. Lower risk of bowel leak although there is a staple line along the length of the stomach to contend with – the risk of leak from this line is lower compared to traditional bowel-bowel anastomosis

2. Lower risk of malabsorption from crucial vitamins, minerals and of course calories as the bowel is not re-routed as in RYGB

3. Shorter procedure time and shorter learning curve due to the reduced technical complexity of this surgery compared to RYGB

Short-term results of the randomised prospective multicentre study comparing laparoscopic sleeve gastrectomy and gastric bypass in the treatment of morbid obesity demonstrates that weight loss, resolution of diabetes, hypertension and hypercholesterolemia are not significantly different between RYGB and VSG.¹

Like the RYGB, the vertical sleeve gastrectomy, reduces the size of the stomach and therefore reducing the amount of calories one can consume therefore promoting weight loss via a physical mean. Unlike gastric bypass, this surgery is purely restrictive and does not alter the gut anatomy. At a cellular level, though it does not have as big an impact as gastric bypass, some effects have been shown (Figure 4).

Overall, recent analysis by international bariatric surgery studies provides reassurance that bariatric surgery is safe with an acceptable mortality rate of 0.08% and leakage rate below 2%.

Since 2008, our weight loss program has seen 650 cases in Singapore General Hospital. We have had no mortality to-date and our complications rate is well below 1%. This is comparable to most United States Centers of Excellence.

I hope emerging data on obesity surgery will raise awareness in other medical specialties and also in the general public. We also hope that it can been seen that there is some value in surgery for the treatment of not only obesity but also related medical diseases such as diabetes and therefore should be considered not only as ‘last resort’ but mainstream therapy.

GPs can call for appointments through the GP Appointment Hotline at 6321 4402 for more information.

References

1. Schauer PR, Bhatt DL, Kirwan JP, et al. Bariatric surgery versus intensive medical therapy for diabetes–3-year outcomes. N Engl J Med. 2014;370(21):2002–2013.
2. Ikramuddin S, Korner J, Lee WJ, et al. Roux-en-Y gastric bypass vs intensive medical management for the control of type 2 diabetes, hypertension, and hyperlipidemia: the diabetes surgery study randomized clinical trial. JAMA. 2013;309(21):2240–2249.
3. Mingrone G, Panunzi S, De Gaetano A, et al. Bariatric-metabolic surgery versus conventional medical treatment in obese patients with type 2 diabetes: 5 year follow-up of an open-label, single-centre, randomised controlled trial. Lancet. 2015;386 (9997):964–973.
4. Sjöström L, Narbro K, Sjöström D, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Eng J Med. 2007;357:741– 752.
5. Adams TD, Gress RE, Smith SC, et al. Long-term mortality after gastric bypass surgery. N Eng J Med. 2007;357:753–761. 6. Lee S Y, Lim C H, Pasupathy S et al. Laparoscopic sleeve gastrectomy: a novel procedure for weight loss. Singapore Med J 2011; 52(11) : 794-800
7. Himpens J, Dobbeleir J, Peeters G. Long-term results of laparoscopic sleeve gastrectomy for obesity. Ann Surg 2010; 252:319-24. 8. Chin Hong Lim, Cyrus Jahansouz, Anasooya A. Abraham et al. The future of the Roux-en-Y gastric bypass. Expert Review of Gastroenterology & Hepatology 2016; 10:7, 777-784
8. Chin Hong Lim, Cyrus Jahansouz, Anasooya A. Abraham et al. The future of the Roux-en-Y gastric bypass. Expert Review of Gastroenterology & Hepatology 2016; 10:7, 777-784

Dr Lim Chin Hong is a Consultant Surgeon in the Department of Upper Gastrointestinal & Bariatric Surgery, Singapore General Hospital (SGH). He completed his medical degree and basic surgical training at the University College of Dublin, Ireland in 2006 following which he embarked on a year-long research with Professor Desmond Winter and the esteemed Professor John Hyland at the St Vincent’s University Hospital.

Dr Lim was granted a training position at the Johns Hopkins Hospital, Baltimore in 2009 and has had the privilege to work with the grandmasters of surgery – Dr John Cameron and Dr Pamela Lipsett. Following this, Dr Lim returned to SGH to complete his advanced surgical training in 2014 and joined the Department of Upper Gastrointestinal & Bariatric Surgery as Associate Consultant.

Under the expert tutelage of bariatric surgeon, Dr Sayeed Ikramuddin and advanced endoscopist, Dr Martin Freeman, he completed a year of accredited fellowship at the University of Minnesota in 2015 in which he gained hands-on experience of over 200 cases of complex bariatric surgical cases and advanced foregut endoscopy.

His main clinical interests include alimentary tract surgery, with a special interest in minimally invasive surgery, upper gastrointestinal and bariatric surgery.