Bariatric surgery

surgery for severe, refractory obesity

The risks of severe obesity are well known. Helping patients to lose weight is never easy but surgery must be regarded as a last resort. NICE accepts that it has a place and evidence grows of its potential value as part of a treatment plan. Long term follow-up and personal discipline are still needed.

Epidemiology: A BMI between 25 and 30 is defined as overweight, over 30 is obese and a BMI over 40 is defined as morbidly obese. A person with a BMI of between 40 and 50 weighs literally twice their ideal weight.
According to NICE,1 in 1998, an estimated 0.6% of men and 1.9% of women in England and Wales had a BMI of 40 or more. This represents 124,000 men and 412,700 women or 2500 people for a typical primary care trust population of 200,000. The prevalence of obesity is rising as the average BMI increases. Between 1994 and 1998 the average BMI increased by 0.44 for men and 0.57 for women.
In the USA the figure for morbid obesity in 20004 was given as 5% of the total population.2
In recent years much publicity has been given to the very real and serious and rapidly growing problem of childhood obesity.
In 2002 there were around 200 such operations performed in the UK annually and many were privately funded.

Risk factors: Risks are well known and many are listed by NICE.1 Obesity carries an increased morbidity and mortality. Risk rises for cardiovascular disease, hypertension, type 2 diabetes, various cancers, musculo-skeletal disease, reproductive disorders and respiratory disorders. Metabolic syndrome X and polycystic ovary syndrome have cardiovascular and other risks. In the young we are seeing type 2 diabetes in adolescence, called MODY ( maturity onset diabetes in the young). In addition, people with a BMI greater than 35 have a rate of mortality at any given age double that of someone with a healthy BMI of 20 to 25. Obesity decreases quality of life. The social stigma attached to obesity produces prejudice and discrimination. It adversely affects mobility, employment and psychosocial wellbeing, with many obese people left feeling depressed, defensive and unable to live life to the full.

Morbid obesity occurs when the intake of calories substantially exceeds expenditure over a long period of time and patients who complain that, "I scarcely eat enough to keep a sparrow alive," are still in denial, not facing reality and not likely to benefit from any intervention.

Criteria for treatment: NICE1 recommend that such treatment may be offered if the patient fulfils all the following criteria:
this type of surgery should be considered only for people who have been receiving intensive management in a specialised hospital obesity clinic
individuals should be aged 18 years or over
there should be evidence that all appropriate and available non-surgical measures have been adequately tried but have failed to maintain weight loss
there should be no specific clinical or psychological contra-indications to this type of surgery
individuals should be generally fit for anaesthesia and surgery
individuals should understand the need for long-term follow-up.

Surgery should normally be reserved for those with a BMI of 40 or more but NICE accept that it may be offered to those with a BMI in excess of 35 if they have associated morbidities that may benefit from weight reduction.

Operations: A number of operations have been devised over the years and modifications have been made. This diversity is one complicating factor when trying to analyse the evidence. Criteria for acceptance or rejection for operation vary. Another problem is that the surgery is just one of many components of the management plan. A PubMed search for "bariatric surgery systematic review" yielded over 100 references published in 2005 alone. It is valid to ask why the world needs so many systematic reviews and the answer would seem to lie in the interpretation of the data.
Surgical procedures can be divided into categories:
Malabsorptive surgery bypasses parts of the gastrointestinal tract to limit the absorption of food.
Restrictive surgery reduces the size of the stomach so the feeling of fullness occurs with less food. Malabsorptive procedures include jejunoileal bypass, gastric bypass and biliopancreatic diversion, while restrictive procedures include gastroplasty and gastric banding. There is an increasing trend towards using laparoscopic rather than open techniques.
Endoscopic placement of something in the stomach. This tends to be a shorter procedure, requiring sedation rather than general anaesthesia.

Pre-operative assessment: Careful assessment is essential. Motivation is mandatory and yet failure to loose weight before operation should not be seen as a reason to refuse surgery. The patient must see it as an aid to dietary control rather than a magical cure or yet another hurdle to stumble over and deny any personal responsibility. "I even had an operation but it didn't work."
Morbidity and mortality can be reduced by careful selection of patients but it may be those most at risk who are most at need.

Operative risk: Postoperative care is vital. It includes managing complications as they occur but also dietary and possibly psychological advice to help modify eating habits. There may be complications such as vomiting, dumping syndrome and diarrhoea, especially after malabsorptive procedures.
People who are so grossly obese are at increased risk of almost every possible risk after surgery including chest infection, urinary tract infection, deep vein thrombosis and pulmonary embolism, wound infection and dehiscence. These can probably be reduced by laparoscopic techniques but this is not easy with such gross obesity and laparoscopic surgery may take rather longer, increasing risk associated with time on the operating table. Clinical Evidence states that complications are common but the risk of death is 0 to 1.5%.3 Perioperative complications were common, including: subphrenic abscess (7%), atelectasis or pneumonia (4%), wound infection (4%), and pulmonary symptoms (6.2%).

Benefits of surgery: As mentioned previously, surgery is just a part of management and so it is inappropriate to call comparisons medical versus surgical treatment. With so many reviews it is difficult to know where to turn but Clinical Evidence3 found that, by and large, surgery produced better weight loss and that it was sustained for longer compared with very low calorie diets alone.
The same team from Clinical Evidence compared laparoscopic with open surgery.4 They found consistent evidence that laparoscopic surgery reduced the incidence of wound and incisional hernia complications compared with open surgery but numbers were too small to compare other complications. There was no difference in resultant weight loss.
Another systematic review and meta-analysis concluded that effective weight loss was achieved in morbidly obese patients after undergoing bariatric surgery and that a substantial majority of patients with diabetes, hyperlipidaemia, hypertension, and obstructive sleep apnoea obtained complete resolution or improvement.2
NICE summed up the problems of poor evidence with recommendations for further research with the words, with few exceptions, studies of surgery for obesity have been uncontrolled and short-term with no comparators. Carefully planned and executed randomised controlled trials comparing obesity therapies with the best alternative modern treatments and with currently standard non-surgical treatment are required and should be started soon. Randomised controlled trials are required to compare different surgical techniques with regard to effectiveness, costs and quality of life of patients in both the short and long term.

Surgery in the young: Health promotion for children and adolescents is obviously failing as obesity becomes an epidemic, even in the young. NICE give 18 as a threshold for surgical intervention. In the young, dietary modification, exercise programmes and cognitive and behavioural therapy remain the basis of management but a considered paper from Australia concludes that Bariatric surgery may be indicated in carefully selected, older, severely obese adolescents.5

Implantable gastric balloon: The Bioenterics gastric balloon is placed in the stomach at endoscopy and it is inflated to give a feeling of fullness. The procedure takes 10 to 20 minutes and so is shorter and safer than surgery. An Italian double blind crossover trial in which patients were on a 1,000 calories diet but also had a balloon placed that was either inflated to 500ml or not showed significantly greater weight loss when the balloon was inflated.6

Implantable gastric stimulation: Antral gastric stimulation was first used experimentally to reduce spontaneous feeding in pigs7 but after 10 years of clinical use it was reported to have achieved significant weight loss without side-effects, with improvement of insulin sensitivity and with reduction of gastro-oesophageal reflux.8 The physiological mechanism is poorly understood and the technique is in its infancy to the extent that much of the literature still relates to animal experiments. It does seem that this technique offers much promise for both obesity and gastroparesis.9 The technique may be more acceptable in young people but it must have appeal to all ages. However, it is not a substitute for diet, exercise, and behavioural change.10

Economic implications: NICE does not shy away from financial costs.1 Obesity has considerable costs for society, both direct, in terms of healthcare, and indirect, in terms of earnings lost through mortality or sickness. Direct costs of obesity in England in 1998 have been estimated at £480 million, or 1.5% of NHS expenditure, and indirect costs at £2.1 billion. NICE found 4 papers about cost-effectiveness of such procedures but all had flaws. Modeling for projections relating to the NHS were based on many assumptions. They thought that 600,000 people have a BMI over 40 but that number again may have a BMI over 35 plus a related morbidity and this 1.2 million could grow by 5% per year. Previous studies suggesting take up of operations at between 2 and 4% of this group may be an underestimate for the NHS. Cost are around £5,500 per procedure, over and above the cost of other continuing care. Capacity will have to rise sharply to meet demand and costs could rise from £1.7 million in the first year to £27 million after 8 years. These calculations are based on very rough guesses about uptake and assuming that other, cheaper techniques, such as the endoscopic placement of balloons or pacers, are not used.