Is obesity a problem?

Obesity has overtaken cigarette smoking as the most significant public health problem in Western Society.  Obesity is related to many diseases such as type two diabetes, high blood pressure, high cholesterol, sleep apnoea, fatty liver disease, polycystic ovaries, degenerative arthritis and is a significant risk factor for certain cancers and premature death.  Obesity is defined as having a body mass index (BMI) greater than 30.

Is there a solution?

Lifestyle modification through diet and exercise is essential for any weight-loss strategy to work.  Unfortunately diet and exercise alone rarely succeed in providing durable and significant weight-loss.  At this point there is no effective medical therapy.  Surgery has become more widely accepted, not because it is a “quick fix” or an “easy way out”, but because there is the highest level of evidence supporting its role in significantly reducing weight, improving health, and reducing the risk of premature death.

Who should consider surgery?

• BMI>40 (morbid obesity)
• BMI>35 with significant health problems related to weight
• Age 18-65
• Previous attempts at weight loss
• Fit for surgery (no end-stage organ failure – heart, lung, liver)
• Committed to lifestyle change
• Realistic expectations
• Full understanding of all procedures and their risks

What are the operations?

Most weight-loss surgery is now performed as keyhole surgery. Gastric Banding is the most commonly performed operation.  It is the safest form of weight-loss surgery, and averages 50% of excess body-weight loss by 3 years after surgery. Gastric Bypass is the “gold standard” operation and averages 70% of excess body-weight loss by 2 years after surgery.  Sleeve Gastrectomy is a newer technique with early results similar to gastric bypass.  While there is good data for gastric banding and gastric bypass to beyond 10 years, there is no such evidence for sleeve gastrectomy at this point.

What are the risks?

Any form of surgery carries with it the risk of compications and also the chance of failure.  Specific operations have differing types and rates of compications.  Gastric banding involves a prosthetic material which is at risk of infection, slippage and erosion.  Gastric bypass and sleeve gastrectomy involve joining and/or removing sections of stomach and these areas may leak causing significant problems.  Complications generally require re-operative surgery which may be via keyhole surgery (laparoscopy) or through a large incision (laparotomy).  They may require management in an Intensive Care Unit. The overall rate of complications is very low, but should be discussed with your surgeon.  The risks of obesity far outweigh the risks of surgery and this has been demonstrated in numerous scientific trials.

How do you get to surgery?

This practice has produced an information DVD (call 49478177 for your copy). Once you have viewed the DVD, a referral to a surgeon is necessary from you local doctor.  You will see the surgeon at least twice to discuss options and suitability.  You will see a dietician and a psychologist.  Two weeks before surgery you start Optifast (a very-low calorie meal replacement) in order to shrink the size of your liver and make the surgery as safe as possible.  You are admitted to hospital on the morning of surgery.  The surgery takes between one (gastric banding, sleeve gastrectomy) and four (gastric bypass) hours.  You go home between one (gastric banding) and three (sleeve gastrectomy) days after surgery.  Most people are back at work by two weeks post-op.

What is the follow-up?

You will need to see the dietician every two weeks initially as you progress through dietary phases: liquids, then purees, then soft food.  It is important to maintain this contact to monitor nutrition down the track.  Vitamin and mineral deficiencies can occur and may require treatment.  Hair loss is not uncommon with rapid weight-loss.  Post-menopause, women who have weight-loss surgery are at risk of osteoporosis.  Symptomatic gallstones occur in 10% of people after surgery.  A small proportion of people develop troublesome folds of excess skin. Gastric bands require regular adjustment.  For all these reasons, regular ongoing follow-up with your surgeon is essential for a successful result.

Obesity surgery: the 21st century evidence

Twenty-five percent of the adult Australian population are obese (body mass-index (BMI) greater than 30 kg/m2) (1).  Obesity is a significant risk factor for the metabolic syndrome and other diseases.  Weight-loss (bariatric) surgery provides durable reduction in weight and remission of obesity related co-morbidities (2,3,4).  Current debate centres on the application of bariatric surgery in the non-morbidly obese population and the choice of operation.

Bariatric surgery is indicated for morbidly obese patients (BMI>40) who have failed non-surgical weight loss.  In this patient group there is good evidence that it improves quality of life and prolongs survival (4,6).  Surgery is also indicated in those with a BMI>35 with significant obesity related co-morbidities.  There is some evidence to recommend bariatric surgery to any obese non-insulin dependent diabetic (9,10), but this has yet to be tested in large prospective trials.

There are three bariatric procedures commonly performed in Australia: the adjustable gastric band (AGB), the roux-en-Y gastric bypass (RYGBP), and the sleeve gastrectomy (SG).  These procedures are generally performed laparoscopically, although open surgery is sometimes used in the revisional setting.  All three operations act primarily by restricting the volume that can be eaten.  Primarily malabsorptive operations, such as the bilio-pancreatic diversion, have been associated with significant morbidity and mortality and are not routinely performed in this country.  The vertical banded gastroplasty (“stomach stapling”) is now obsolete.

The AGB accounts for 95% of bariatric surgery in Australia (5).  This popularity relates to its perceived safety.  There is no doubt that the AGB is the safest weight-loss operation (Table 1), but revisional surgery is required at a rate of 1-2% per year.  This is mostly for slippage of the stomach under the band, erosion of the band into the stomach, or  inadequate weight-loss.  Revisional bariatric surgery is more complex than primary surgery and there is a four-fold increase in morbidity and mortality (7).

Predicted weight-loss with the AGB is 50% of excess body weight (EBW) over three years (8).  This is achieved with careful follow-up and adjustment of the band to ensure that the degree of restriction is appropriate. The AGB works by transiently obstructing the passage of solid foods, which stretches the gastric wall above the band thereby signaling satiety.  An AGB that is too tight leads to maladaptive eating: softer textured foods are favoured as solids precipitate pain, reflux or regurgitation.  This bypasses the satiety mechanism leading to inadequate weight-loss, and probably increases the rate of AGB slippage due to recurrent vomiting.  Regular dietetic review is mandatory to monitor nutritional intake and help facilitate changes in eating behaviours (e.g. avoiding grazing, eating slowly, eating to satiety rather than fullness).  Band adjustments are necessary for the life of the band: generally, three to four adjustments are performed in the first year and one or two per annum after that.

Four percent of the Australian population currently have diabetes and this number is predicted to rise significantly (1).  Bariatric surgery cures a significant proportion of type two diabetes (9-11).  A randomized controlled trial (RCT) by Dixon et al (10) compared the AGB to conventional therapy in 60 obese patients (BMI 30-40).  Over a two year follow-up period 73% of the surgically treated group achieved remission compared to 13% of the conventionally treated group.  The same group have published the cost-effectiveness of surgery as a treatment for type two diabetes and concluded that it is a dominant intervention: one that saves money ($2400) and prolongs life (1.2 quality-adjusted life-years).

The RYGBP is the most established bariatric procedure; gastric bypass for weight loss has been performed since the 1960s.  Predicted weight loss averages 65% EBW, mostly by 18 months post-op (2) and there is a sustained reduction of 30% of total body-weight at 10 years (4).  A small gastric reservoir is created and a roux limb of jejunum is anastomosed to it.  While the primary effect of surgery is to restrict the volume of food eaten, undigested food entering the roux limb can lead to a dumping syndrome which acts as a deterrent to over-eating calorie rich foods.  Bypass of the proximal small bowel leads to a reduction in putative diabetogenic factors which leads to rapid resolution of type two diabetes, even before significant weight-loss occurs (9,12).  Remission of diabetes is seen in 75-95% of patients (9,11).

Laparoscopic RYGBP is technically more demanding than AGB, and the complications of surgery (anastomotic leak, stomal ulceration, internal hernia) are potentially life threatening.  Nutritional sequelae such as iron deficiency, vitamin B12 deficiency, osteoporosis and gallstone formation occur with greater frequency than with the AGB, and mandate careful follow-up.

Laparoscopic SG is a relatively new procedure.  It originated as the first stage of a two stage procedure in the super-obese (13), but is now increasingly performed as a definitive bariatric operation.  It is the only non-reversible bariatric operation: it involves removal of the greater curvature of the stomach leaving a narrow gastric tube.  The fundus of the stomach is the primary site for ghrelin secretion (14).  Ghrelin is the only identified orexigenic hormone (“hunger hormone”) and SG has been shown to lead to sustained reduction in ghrelin levels and reduced hunger compared to other bariatric operations (15,16).  Karamanakos et al (16) enlisted 32 patients in a double blind RCT comparing SG with RYGBP and found better weight loss in the SG group at one year (70% vs 60%).  Himpens et al (17) compared SG with AGB (80 patients) and found better weight loss at three years (66% vs 48%).  The long term results of the SG are yet to be published: gastric reflux and dilatation of the sleeve have been reported, and the incidence of weight regain is not yet known.  The SG sits between the AGB and RYGBP in terms of operative morbidity: anastomotic leak from the long gastric staple line has been reported in up to 1% of cases, however there is no potential for procedure-related complications once convalescence is complete (cf. RYGBP where there is up to a 5% lifetime incidence of internal hernia requiring re-operation).  This may make the SG an appropriate choice for people living remotely.

Bariatric surgery in Australia is still dominated by the AGB, and with good reason, as Australia’s published results for weight-loss with the AGB are the best in the world (2,8).  The AGB is a prosthetic device and a certain proportion will require revision.  As the cohort of patients requiring revisional surgery grows, so will the prevalence of RYGBP.  There are no large multi-centre trials comparing the various operations as primary procedures, and these are unlikely to happen until the surgery becomes widely available in the public sector.  A tailored approach to the choice of primary operation based upon patients’ expectations of weight loss, ability to attend follow-up, co-morbidities, presence of reflux and initial BMI may lead to a reduction in the need for revisional surgery.

References

• Australian Bureau of Statistics. National Health Survey: Summary of Results, 2004-05. Canberra: ABS; 2006. ABS Cat. No.:4364.0
• Colquitt JL, Picot J, Loveman E, Clegg AJ.  Surgery for Obesity.  Cochrane Database of Systematic Reviews Volume (4), 2009
• Buchwald H, Avidor Y, Braunwald E, et al. Bariatric surgery: a systematic review and meta-analysis. JAMA. 2004;292:1724-37.
• Sjostrom L, Narbro K, Sjostrom CD, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med. 2007;357:741-52.
• Medicare Australia Statistical Reporting. URL: www.medicareaustralia.gov.au/statistics accessed April 2010
• Christou NV. Impact of Obesity and Bariatric Surgery on Survival. World J Surgery (2009) 33:2022-27.
• Brolin RE. Cody RP.  Weight loss outcome of revisional bariatric operations varies according to the primary procedure.  Annals of Surgery. 248(2):227-32, 2008 Aug
• O”Brien PE. Dixon JB. Brown W. Schachter LM. Chapman L. Burn AJ. Dixon ME. Scheinkestel C. Halket C. Sutherland LJ. Korin A. Baquie P.  The laparoscopic adjustable gastric band (Lap-Band): a prospective study of medium-term effects on weight, health and quality of life.  Obesity Surgery. 12(5):652-60, 2002 Oct
• Buchwald H. Estok R. Fahrbach K. Banel D. Jensen MD. Pories WJ. Bantle JP. Sledge I.  Weight and type 2 diabetes after bariatric surgery: systematic review and meta-analysis.  American Journal of Medicine. 122(3):248-256.e5, 2009 Mar
• Dixon JB. O”Brien PE. Playfair J. Chapman L. Schachter LM. Skinner S. Proietto J. Bailey M. Anderson M.  Adjustable gastric banding and conventional therapy for type 2 diabetes: a randomized controlled trial.  JAMA. 299(3):316-23, 2008 Jan 23.
• Gan SSH, Talbot ML, Jorgensen JO. Efficacy of surgery in the management of obesity related type II diabetes mellitus. ANZ J. Surg. 2007; 77: 958-62.
• Rubino F. R”bibo SL. del Genio F. Mazumdar M. McGraw TE.  Metabolic surgery: the role of the gastrointestinal tract in diabetes mellitus.  Nature Reviews Endocrinology. 6(2):102-9, 2010 Feb.
• Regan JP. Inabnet WB. Gagner M. Pomp A.  Early experience with two-stage laparoscopic Roux-en-Y gastric bypass as an alternative in the super-super obese patient.  Obesity Surgery. 13(6):861-4, 2003 Dec.
• Kojima M. Hosoda H. Date Y. Nakazato M. Matsuo H. Kangawa K.  Ghrelin is a growth-hormone-releasing acylated peptide from stomach.  Nature. 402(6762):656-60, 1999 Dec 9.
• Nakazato M. Murakami N. Date Y. Kojima M. Matsuo H. Kangawa K. Matsukura S.  A role for ghrelin in the central regulation of feeding.  Nature. 409(6817):194-8, 2001 Jan 11.
• Karamanakos SN. Vagenas K. Kalfarentzos F. Alexandrides TK.  Weight loss, appetite suppression, and changes in fasting and postprandial ghrelin and peptide-YY levels after Roux-en-Y gastric bypass and sleeve gastrectomy: a prospective, double blind study.  Annals of Surgery. 247(3):401-7, 2008 Mar.
• Himpens J. Dapri G. Cadiere GB.  A prospective randomized study between laparoscopic gastric banding and laparoscopic isolated sleeve gastrectomy: results after 1 and 3 years.  Obesity Surgery. 16(11):1450-6, 2006 Nov.