Information for general practitioners

 

Definition of obesity

Obesity is a chronic disease requiring multidisciplinary and long-term management.

For selected patients, obesity surgery (or bariatric surgery or weight loss surgery), combined with changes in eating habits and increased physical activity, is an effective weight loss method.

Surgery is the only current treatment that achieves long-term weight control in over 85 per cent of morbidly obese patients.

It can also be used to control or improve certain co-morbidities, to improve quality of life and reduce obesity-related mortality.

BMI

Obesity is defined by a BMI ≥ 30 kg/m².

Calculation of BMI, target weight and excess weight allows patient treatment goals to be established. Location of excess fat is also a risk factor in obesity, therefore it is important to record waist diameter.

Classification BMI (kg/m²)

Success following an operation is generally defined as loss of over 50 per cent of excess weight or maintaining a BMI < 35.

 

Making the decision to operate

Six conditions are required to benefit from bariatric surgery:

• BMI ≥ 40 kg/m²
  OR
  BMI ≥ 30 to 35 kg/m²
  with at least one comorbidity that is likely to improve following surgery (high blood pressure, obstructive sleep apnoea syndrome, type 2 diabetes, incapacitating joint disorders, non-alcoholic steatohepatitis, etc.)

• failure of medical, nutritional, dietetic and psychotherapeutic treatment that has been properly conducted for six to 12 months (weight loss is not sufficient or weight loss is not maintained)
• multidisciplinary preoperative assessment and management for several months
• patient is well informed
• patient has understood and accepted the need for lifelong surgical and medical follow-up
• acceptable operating risk.

Contraindications, some of which may be temporary:

• severe cognitive or mental disorders
• severe and non-stabilised eating disorders
• alcohol or psychoactive substances dependence
• diseases that are life-threatening in the short and medium term
• contraindications to general anaesthesia
• absence of identified prior medical management of obesity and likely inability of the patient to participate in lifelong medical follow-up

Preoperative medical, psychological and educational management for several months is necessary:

• assessment and management of comorbidities (high blood pressure, OSAS, diabetes, etc.), assessment of eating behaviour and management of any eating disorder, nutritional and vitamin assessment and correction of any deficits, upper gastrointestinal endoscopy with tests for Helicobacter pylori
• psychological/psychiatric assessment: for all patients who are candidates for obesity surgery
• therapeutic education programme : diet and physical exercise.

Deciding to operate:

A decision is made following multidisciplinary medical and surgical discussion and consensus that may involve the general practitioner.

 

Surgical techniques

Combination of metabolic and restrictive

Mixed techniques combine gastric restriction with neuro-hormonal effects through the creation of a bypass, diversion or excision of metabolically active cells:

• Gastric bypass
• Sleeve gastrectomy or longitudinal gastrectomy

Restrictive only

The techniques based primarily on gastric restriction are used to reduce food intake by reducing gastric capacity without neuro-hormonal effects:

• Adjustable gastric banding
• Vertical banded gastroplasty

Laparoscopy is the recommended approach.

Gastric bypass

• international 'gold standard'
• involves construction of a very small 'pouch' from a part of the top of the stomach. This is then joined to the small bowel, bypassing the rest of the stomach and about one metre of the small intestine
• reduces amount that can be eaten at a single sitting, and reduces hunger, probably by affecting the hormones in the gut
• good balance between efficacy and the durability of the weight loss.

Advantages

• effective, long-lasting weight loss for most people, and most obesity-related health problems improve
• improved quality of life
• normal, especially healthy food can still be eaten, just in small volumes.

Disadvantages

• vitamin supplements should be taken daily, and usually iron and calcium tablets
• the risk of gastric bypass surgery is similar to elective hip or knee surgery (1 in 200 to 1 in 1000 risk to life)
• early complications can occur soon after the surgery due to leaks from where the gut is joined; bleeding; infection; or blood clots
• late complications can occur due to blockages of the bowel. not easily reversed
• not everyone is a candidate for laparoscopic bypass; these people may require open surgery or should consider other options
• even this operation can be beaten by eating the wrong foods and failing to keep to the necessary lifestyle changes.

Expected weight loss
About 75 per cent of excess weight

Duration of operation
2 to 3 hours

Number of nights in hospital
2 to 3

Recovery period
1 to 2 weeks off work, occasionally up to 4 weeks

Sleeve gastrectomy

• reduces the size of the stomach from a sac to a narrow tube
• weight is lost because the patient feels fuller earlier after eating, largely due to the smaller size of the stomach. The procedure also reduces some appetite simulating hormones produced by the stomach. Apart from this effect, the stomach digests calories and nutrients in an almost normal way.

Advantages  

• effective weight loss for most people and improvement in many obesity-related health problems improve
• normal (especially healthy food) can still be eaten, just in small volumes
• good option for high-risk patients.

Disadvantages

• vitamin supplements should be taken daily
• long-term outcomes uncertain
• early complications can occur soon after the surgery and be due to leaks from where the gut is stapled, bleeding, infection or blood clots
• irreversible
• even this operation can be beaten by eating the wrong foods and failing to keep to the necessary lifestyle change.

Expected weight loss
About 50 to 75 per cent of excess weight

Duration of operation
2 hours

Number of nights in hospital
1 to 2

Recovery period
1 to 2 weeks off work.

Vertical banded gastroplasty

• also known as stomach stapling 
• no longer performed in New Zealand because of its poor results.

Adjustable gastric banding

• an adjustable band is placed at the upper part of the stomach. The size of the outlet of the upper stomach can be adjusted by adding or removing fluid through a small port placed just under the skin.
• when working well, this lessens feelings of hunger, and allows people to feel full after eating only a small amount of food.
• although a common procedure overseas, gastric banding does not give the sustainable results of the gastric bypass or the sleeve gastrectomy.

For this reason, Auckland Weight Loss Surgery no longer supports or recommends this operation.

Advantages:

• minimal vitamin deficiencies as no part of the bowel is bypassed
• safety: probably no more risk than elective gallbladder surgery and less risk of early complications
• shortest inpatient stay (overnight).

Disadvantages:

• diet very restrictive; most patients cannot eat white bread and chicken. Sometimes the restriction interferes with the ability to eat other foods that are components of a normal diet and many patients are restricted to only soft or sloppy foods that are often high in fat
• it is possible to easily beat the operation by eating sweets/chocolate/ice cream and some people develop a preference for these foods which leads to failure
• these operations do not work so well for older, larger patients with diabetes
• ongoing failure rate due to band slip, band erosion or inadequate weight loss causing up to 5 per cent of bands being removed per year
• weight loss is variable. Average excess weight loss only 45 per cent, many patients fail to lose half their excess weight. This leads to a high rate of dissatisfaction.

 

Benefit/risk ratio of techniques

It is difficult to make a classification of the different techniques based on their benefit/risk ratio.

The more effective procedures are in terms of weight loss (40 to 80 per cent of excess weight), the more complex and risk-prone they are: postoperative complications, risk of nutritional consequences and operative mortality (0 to 1 per cent). Gastric banding is the intervention presenting least risk but it also the least effective.

Morbidity

Early morbidity is mainly linked to digestive perforations and leakage, occlusions, bleeding, and thromboembolic and respiratory complications (atelectasis, etc.).

In the longer term, complications may be surgical (band slippage and/or pouch dilation, anastomotic stenosis, occlusion, migration of the band), nutritional (in particular following metabolic surgery) or psychological.

 

Post surgical follow-up lifelong

This is carried out by the multidisciplinary team that approved the indications for the intervention and by the general practitioner.

Detect complications from the surgical procedure:

• certain symptoms must result in urgent consultation with the surgeon of the multidisciplinary team
• symptoms appearing early: tachycardia, dyspnoea, abdominal pain, confusion or hyperthermia, even in the absence of guarding or tenderness
• symptoms that may appear late: abdominal pain, vomiting, dysphagia, incapacitating gastro-oesophageal reflux.

Prevent and screen for vitamin and nutritional deficiencies

• these can lead to serious neurological conditions
• following metabolic surgery, some nutritional supplementation is recommended for all patients (multivitamins, calcium, vitamin D, iron and vitamin B12 are most common)
• following restrictive surgery, it may be discussed if the results of the clinical and biological assessment warrant it.

Adapt any medicines and their dosage

• bariatric surgery can improve or control certain comorbidities, sometimes only a few days or weeks after the operation (diabetes in particular). These comorbidities must be reassessed early and their treatment adapted
• metabolic surgery can lead to changes in the metabolism of various medicines (antivitamin K, thyroid hormones, antiepileptic drugs, etc.), the dosage of which may require modification in the early post-operative period
• gastrotoxic medicines (aspirin, non-steroidal anti-inflammatory drugs, corticosteroids, etc.) must be avoided as far as possible.

Continue the education of the patient

• follow up diet and physical activity programmes commenced in the preoperative phase by checking, in particular, that they are adapting well to their new eating habits.

Assess the necessity of psychological or psychiatric follow-up

• follow-up recommended for patients who presented with eating disorders or other psychiatric pathologies before the operation.
• follow-up proposed on a case-by-case basis for other patients.
• weight loss can lead to psychological changes that may not be easy to manage. A period of adaptation to the change is often necessary, both for the patient and for their family, friends and colleagues.

If necessary, plan for reconstructive surgery
This is possible 12 to 18 months after obesity surgery, when weight loss has stabilised and in the absence of malnutrition.

 

Contraception after surgery

Contraception is recommended as soon as surgery is planned and then for 12 to 18 months after the operation. The efficacy of oral contraception must be discussed.

If a patient intends to conceive following obesity surgery, we recommend planning nutritional follow-up by the multidisciplinary team before conception, and failing this, at the very start of the pregnancy, during the pregnancy and post-partum.

Obesity surgery is contraindicated for pregnant women.