Chapter 20 – Surgical Treatment of Obesity

Updated January 8, 2012

Background

Obesity is one of the most significant pathogens in the developed world. It causes or exacerbates numerous common and lethal diseases. It can markedly reduce the quality of life and it competes with smoking as the commonest cause of premature death. The prevalence of obesity has increased markedly in the last thirty years. A systematic review of 199 countries in 2008 estimated 502 million people worldwide were obese₁. The World Health Organization projects this number to increase to 700 million by the middle of this decade.
The epidemic is quite recent. In the United States, between 1960 and 1980, there was a relatively modest rise in the number of adults  with obesity, from 12% to 14% only.  This number has more than doubled since 1980₂. Currently, approximately 80 million, 34% of the adult population, are obese₃ and this number is estimated to increase to more than 140 million by 2030₄. The direct health care costs are estimated to be $75 billion per year in 2003. These would rise to $140 billion per year and it would be an associated loss of productivity (indirect costs) of $580 billion₄  Based on the Health and Wellness Survey in 2008 there is estimated to be  loss of 1.7 - 3.0 million productive person-years in the USA, representing a cost of $390 - $580 billion due to the current state of obesity₄ .
The morbidity caused by obesity makes it our greatest current health challenge because of its direct contribution to many chronic, debilitating and life-threatening diseases. These include type 2 diabetes, cardiovascular diseases such as ischemic heart disease, stroke, hypertension and dyslipidemia and several common cancers. The health care costs are now a major component of health budgets across the developed world. Currently there is no non-surgical method for predictably achieving major weight loss in the obese and maintaining that weight loss for an extended period. Current programs involving diet, behavioral modification, exercise and activity, with or without drug supplementation, are able, at best, to achieve a modest weight loss which is generally sustained only for the duration of the program.
In this chapter I will review the surgical options, their strengths and weaknesses, to provide a framework of evidence that enables a logical treatment approach to this major healthcare challenge. In doing so, I will seek an alignment of  the views of health professionals and the general community so that they recognize obesity as a disease and not a sign of personal failing, they acknowledge the severity of this disease and they recognize the spread of  invasiveness and risk and effectiveness associated with options for surgical treatments. 
Surgical methods have been known to achieve substantial and durable weight loss for more than half a century and yet they have not achieved a significant impact on community health. Currently, less 1 in a 1000 world-wide and less than 1 in 250 in the USA and Australia of those who would benefit by treatment are accepting the surgical approach.  During this time the risk to benefit ratio has become much more favorable and the cost to benefit ratio is also favorable. It is time for a change and the data are there to justify a change.

An historical perspective of bariatric surgery

Although the weight loss that accompanied surgery, particularly if it involved the stomach or small intestine, had been noted for as long as the procedures existed, a direct use of surgery for the specific purpose of weight loss - bariatric surgery - really began in 1954 with the small bowel bypass procedure. It can be seen to pass through three phases so far. The small bowel bypass phase was replaced by the gastric stapling phase in the late 1960s and then the introduction of laparoscopic surgery and gastric banding led to the third phase.

The Initial Phase (1950 – 1970) – Small bowel bypass.

Surgical management of obesity began with the introduction of the jejunoileal bypass (JIB) in the 1954₅. In this procedure the proximal jejunum was diverted to distal part of the gut, leaving a long segment of excluded small intestine and a marked reduction in absorptive capacity. Many variations existed. Many variations existed but in a typical procedure the proximal 35 cm of proximal jejunum was joined end-to-side to the last 10 cm of ileum. The JIB procedures represented the best and the worst of bariatric surgery. Major and sustained weight loss was achieved and there were impressive health benefits, particularly in relation to lipid metabolism. However it was associated with serious side-effects including copious offensive diarrhea, electrolyte imbalances, oxalate calculi in the kidneys and progressive hepatic fibrosis with eventual liver failure. For these reasons this group of procedures was generally abandoned by the 1970s in favor of stomach stapling procedures 6-10.

The Middle Phase  (1970 – 1990) – Stomach stapling.

The Roux en Y gastric bypass (RYGB) operation was introduced  by Edward Mason in 1960₁₁. In this procedure the stomach was completely partitioned into a small upper gastric pouch, draining into a Roux–en-Y limb of proximal jejunum of variable length from 40 to 150 cm, and a distal excluded stomach. This procedure provided a hybrid between the malabsorptive approach of JIB and later, more purely restrictive, operations. It has undergone various modifications over the subsequent 40 years and still serves us well as an effective anti-obesity operation. However its drawbacks of perioperative death and  significant perioperative and late morbidity, although markedly less threatening than those of JIB, have been nevertheless sufficient to cause most of the obese to stay away.  
Dr Mason and his colleague, Dr Printen, then introduced a purely restrictive operation of gastroplasty in 1973₁₂. The procedure involves partitioning the stomach into a small upper pouch draining through a narrow stoma into the remainder of the stomach. Numerous variations of this procedure have followed, the most significant variant being the vertical banded gastroplasty (VBG) which was first described by Dr Mason in 1982₁₃ . It was hoped that this group of operations would provide greater short and long term safety and yet retain the power of gastric bypass. Unfortunately both randomized controlled trials and observational studies have consistently shown that it has failed in both aspirations14-17.
In the meantime there was a resurgence of malabsorptive surgery with Italian surgeon,  Nicola Scopinaro, introducing the biliopancreatic diversion procedure (BPD) in 1976₁₈. It too has undergone change with time and experience. The basic procedure involves distal gastrectomy leaving a proximal gastric pouch of 200 – 500 ml, a 200 cm length of terminal ileum anastomosed to the gastric pouch and the biliopancreatic limb entering at 50 cm from the ileocecal valve₁₉. The most notable remodeling of the procedure has been the so-called duodenal switch variant (BPD-DS) proposed by Picard Marceau’s group in 1993₂₀, ₂₁ in which a longitudinal gastrectomy enabled retention of the gastric antrum with, hopefully, controlled gastric emptying, and the ileal limb was anastomosed to the proximal duodenum. The benefit of this variation remains controversial.

The Current Phase (1990 - present) – Laparoscopic and adjustable procedures.

This phase is characterized by the advent of the laparoscopic adjustable gastric band (LAGB) with the particular features of minimal anatomical disturbance, adjustability and potential reversibility₂₂, ₂₃ . Also, there has been the introduction of a laparoscopic approach to gastric bypass₂₄ and biliopancreatic diversion₂₅.  The reduced invasiveness and increased safety of these approaches has led to a major rise in the use of bariatric surgery for obesity across the world. In the United States the estimated total bariatric procedures in 1990 was 30,000. The total for 2008 was estimated to be 220,000 cases₂₆
Adjustable gastric banding had first been proposed by two Austrian surgical researchers, Szinicz and Schnapka, in 1982₂₇. The idea was brought into clinical practice as an open operation by  Lubomyr Kusmak in 1986₂₈. It did not attract major interest until the advent of the technology that enabled the performance of complex laparoscopic surgical procedures became widespread in the early 1990s. The BioEnterics® Lap-Band ® system (LAGB) was specifically designed for laparoscopic placement and was introduced into clinical practice by Mitiku Belachew from Huy, Belgium in September 1993. Because of the dual attractions of a controlled level of effect through adjustability and of laparoscopic placement without resection of gut or anastomoses, through the 1990s this procedure rapidly became the dominant bariatric procedure in all regions of the developed world except the USA, where its introduction was delayed until regulatory requirements were completed in June 2001.
In the meantime, laparoscopic RYGB  was introduced by Wittgrove and Clark in 1994₂₉. The technical challenge of completing the gastrojejunostomy laparoscopically has been variously managed by transoral passage of a circular stapler, end-to-end or side-to-side stapling transabdominally or a simple hand-sewn anastomosis.  As the technical challenges of the laparoscopic approach were overcome, this procedure became the dominant approach in the USA until it recently has been overtaken by gastric banding. The uptake of laparoscopic RYGB has been less complete in the rest of the world and now, with sleeve gastrectomy on the rise, it seems unlikely it will challenge the less complex procedures.
 Laparoscopic BPD or its DS variant  has remained clinically challenging. The mortality can be high₂₅ and few are now performed₂₆. Most BPD are still performed by open technique and as they represents less than 2% of bariatric surgery worldwide, it is unlikely they will grow beyond that.
Two new procedures have been added in recent years. Vertical sleeve gastrectomy (VSG) is just the first part of the DS variant of the BPD. It was found to lead to good early weight loss and, as it avoids the metabolic consequences of the full procedure, its use has increased. It is expected to be the procedure of choice for more than 15% of bariatric procedures in the USA during 2011. Gastric imbrication has appeared as a possible option during the last two years and very little data on safety or effectiveness are available to date.  It remains to be seen if achieves a significant place in bariatric surgery as a stand-alone procedure or possibly as an adjunct to LAGB.

Current Methods in Bariatric Surgery

1. Laparoscopic adjustable Gastric Banding (LAGB).

The LAGB is the first of the surgical options on table 4 and therefore tends to be preferred ahead of other bariatric procedures on the hierarchy of risk  because of its effectiveness in the setting of a better safety profile, minimal invasiveness and complete and easy reversibility.
The procedure was introduced into clinical practice when Dr Mitiku Belachew with the laparoscopic placement of a Lap-Band in a patient in Huy, Belgium on the 3rd September, 1993. Others quickly followed and soon it was being embraced as an important new procedure. However initially there were significant  gaps in the knowledge of the process of care the LAGB required  and skills in LAGB placement, optimal aftercare and management of late adverse events. It was not known how the band worked or even if it would work. There were no data on optimal placement and fixation.  Protocols for the aftercare process, the adjustment protocols and the education of the patient into the specific requirements for eating and activity after the band were not present.
There has been important growth in knowledge since that time with more than 1,000 peer-reviewed papers defining the LAGB process and outcomes.  It is now more studied than any bariatric procedure with better knowledge of its mechanisms and a higher quality evidence base than all the other bariatric options.
There are a number of adjustable gastric bands available. The principal two, which have approval of the US Food and Drugs Administration for use in the USA, are the Lap-Band ™     (Allergan Inc, Irvine, CA) and the Realize Band™ (Ethicon Endosurgery, Cincinnati, OH).  Others include the Mid-Band, the Heliogast band, the Minimizer band and the AMI band. These are in use principally in Europe.  They lack adequate published data attesting to their effectiveness, they are not approved for use in the USA and so their uptake has been modest. The discussion below will focus primarily on the data from the Lap-Band.
The current version of the Lap-Band, known as the Lap-Band AP (for Advanced Platform), is shown in figure 1.

The LAGB is almost always placed laparoscopically.  Commonly 3 x 5mm, 1 x 10mm and 1 x 15  mm ports are required.  A path is developed from the top of the lesser curve of the stomach to the angle of His, the band is placed around this path, closed and then stabilized at this site with some sutures. The tubing passes to an access port, placed through a 4 cm incision over the left rectus abdominis  muscle and it is sutured to the muscle sheath. The procedure takes 30 -50 minutes to complete and the patient is able to go home at a mean of 2 hours after completion of the procedure₃₀.

2. Roux en Y Gastric Bypass (RYGB)

Gastric bypass combines  a marked reduction in the size of stomach available for food with a narrow stoma passing from the gastric pouch to a Roux en Y loop of jejunum diverting  food from the duodenum and proximal jejunum. In a typical current laparoscopic version (figure 3), the stomach is divided completely by multiple firings of a device which places two rows of staples and cuts  the gastric wall in between. This creates a small proximal gastric pouch of volume of 50ml or less and a large residual stomach, now excluded from the food. A Roux loop of jejunum is formed by dividing the proximal jejunum completely at about 50cm from the duodeno-jejunal flexure, taking the distal aspect of this point of division up to form a small anastomosis with the small gastric pouch and anastomosing the proximal aspect to the more distal jejunum at 50 cm below the gastro-jejunal anastomosis.  The procedure takes 90 -150 minutes and the patient stays in hospital for 2 - 4 days.

3. Biliopancreatic Diversion / Duodenal Switch (BPD/DS)

The BPD contains a "restrictive" component and a "malabsorptive" component.  The restrictive component  is a partial gastrectomy leaving a large proximal gastric segment of between 200 and 500ml. The actual size is only loosely defined. The originator of BPD, Dr Nicola Scopinaro, moved to the "ad hoc gastrectomy" with its wide variability of gastric pouch size after he had treated nearly 1000 patients. He recommended tailoring the gastrectomy to the patient's weight and some physical characteristics. He also recommended tailoring the intestinal lengths₃₁. The validity and effect of these variations has not been reported.
The malabsorptive component consists of division of the small intestine, usually at 250cm proximal to the ileocecal valve, anastomosis of the distal side of this division to the gastric pouch and end-to-side anastomosis of the proximal side of the division to the terminal ileum, usually at 50cm proximal to the junction with the cecum.
In the duodenal switch variant of the BPD (figure 4) a sleeve gastrectomy is performed, preserving the pylorus and proximal duodenum. The distal end of the  transected small bowel is anastomosed to the duodenum. This structure is designed to avoid dumping syndrome but any particular benefit of one version over the other is unclear.

It is the most metabolically severe of the current options and therefore hasn’t proved to be popular with patients or surgeons in spite of favorable published outcomes.  BPD has been available for 30 years₁₈ and yet remains a very minor part of bariatric surgery. Worldwide, it constitutes less than 2% of bariatric surgery₂₆. However, it does generate good weight loss and should be considered on occasions as a second line bariatric surgical option.

4. Sleeve Gastrectomy and other gastroplasties

The sleeve gastrectomy involves excision of approximately 80% of the stomach by using multiple firings of a linear stapler/cutter to separate a narrow tube of the lesser curve of the stomach from the greater curve aspect. The antrum is preserved to maintain gastric emptying. A bougie is placed in the lesser curve segment during the resection to maintain adequate lumen yet achieve a standardised gastric remnant.  The optimal size of this bougie is not yet agreed upon. The procedure is non-adjustable and non-reversible.

Gastric imbrication is a non-resectional variant of the sleeve gastrectomy. The greater curve  vascular pedicles are ligated and then the gastric wall is imbricated using two rows of sutures to create a narrow lumen, similar in size to the sleeve gastrectomy. The costs are reduced by avoiding the use of multiple firings of stapling devices and the risks are expected to be lower by the absence of the stapled closure of divided stomach.

Mechanisms of Action in Bariatric Surgery

Historically, bariatric surgical procedures were all subdivided into two groups. Some were classified as  restrictive, with the creation of a small pouch that limited the size of a meal  and a small opening from that pouch into the rest of the gut so that the transit of food was abnormally delayed. The best model of a restrictive procedure was the vertical banded gastroplasty. Others were described as  malabsorptive, in which the changed anatomy reduced normal macronutrient absorption.  The best example of this was the original jejunoileal bypass. Some procedures are considered to be a hybrid containing both elements, the BPD being an example. Other possible mechanisms were not considered.  This narrow dichotomous concept has happily faded as better research and more careful consideration has led to a much broader understanding of the mechanistic options.
Table 1 provides a list of current known mechanisms. It is undoubtedly incomplete but provides a more up-to-date view of how bariatric surgical procedures can achieve weight loss.

           

1. Mechanisms in Laparoscopic adjustable gastric banding (LAGB)

The band lies at the very top of the stomach, around the cardia and within one cm of the esophago -gastric junction. The access port is place in the subcutaneous layer of the anterior abdominal wall and is accessed by a percutaneous injection.  The primary mechanism of action of the gastric band is by the induction of a sense of satiety, a lack of appetite or hunger₃₂. There are two components to this - satiety and satiation.
Satiety is the state of not being hungry. It is achieved for the LAGB patient by adding or removing of fluid from the system to change  the degree of compression of the band on the gastric wall. When this compression is optimal, it induces a sense of satiety which is present throughout the day.  Although some hunger may develop at times during the day, there is a general reduction of appetite, less interest in food and less concern about not eating. 
Satiation is the resolution of hunger with eating. For the LAGB patient, it is induced by each bite of food as it passes across the band. When the band is optimally adjusted each bite is squeezed across by esophageal peristalsis, generating increased pressure on that segment of the gastric wall. This reduces any appetite that may have been present and induces a feeling of not being hungry after eating a small amount. The combination of these effects allows the person to eat three or less small meals per day. The mean energy intake of the banded patient should be between 1,000 and 1,200 kcals per day₃₃.

Figure 7 shows two views of the Lap-Band AP. On the left, it contains only the basal volume 3ml of saline and on the right it is well inflated band containing 7 ml of saline. The space within which is occupied by the cardia of the stomach.  With 3ml added the internal space has an area of 357cm2. This is reduced to an area of 139cm2 with 7.0ml is present. These two areas represent the limits within which the LAGB is set for most patients. This ability to titrate the level of adjustment against the level of satiety is central to the effectiveness of the band.
The optimally adjusted band modifies the normal transit of a food bolus into the stomach. With normal swallowing, a food bolus is swallowed and carried by oesophageal peristalsis down the esophagus. The lower esophageal sphincter(LES) relaxes and the bolus passes intact smoothly into the stomach. The LES facilitates the final transfer with an aftercontraction. With the band in its correct place with only 1-2 cm of cardia above the upper edge of the band and with the band optimally adjusted (exerting a pressure of between 25 and 35 mm Hg on the gastric lumen₃₄), the esophagus must generate stronger peristalsis and the aftercontraction of the LES become more important. The bolus is squeezed through by these forces. It takes between two and six squeezes to achieve complete transit of a single small bite. This may take up to one minute.

The aftercontraction of the LES is evident. Just part of each bite will transit on each peristaltic sequence. The remainder will reflux into the body of the distal esophagus, generate a secondary peristalsis wave and a further squeeze will occur. After several squeezes the bite will have passed. Importantly, each squeeze generates signals  to the satiety centre of the hypothalamus. A second swallow should not commence until all of the previous bite has passed totally into the stomach below the band.
The signalling of both satiety and satiation to the arcuate nucleus of the hypothalamus does not appear to be mediated by any of the hormones known to arise from the cardia as none has been shown to be increased in a basal state after band placement and none increases post-prandially₃₅.  Vagal afferents are the more probable mediators and, among these, the intraganglionic laminar endings ( IGLEs) demonstrate the characteristics needed to subserve this role₃₆, ₃₇
Figure 9 shows the components of the lower esophageal contractile segment (LECS), an entity described by Dr Paul Burton from extensive study of the "physiology" of the gastric band₃₈. It brings together the key elements that  together generate early onset of satiation after eating. The distal esophagus squeezes each bite of food to the stomach proximal to the band. The lower esophageal sphincter relaxes to allow passage and then contracts to maintain the forward pressure. The proximal segment of stomach maintains tonic contraction and detects the pressure increase. The band maintains an optimal compression to provide sufficient resistance to stimulate afferent signals but not sufficient to stop transit. There should be no restrictive component for normal functioning of the LAGB.

2. Mechanisms of Roux en Y Gastric Bypass (RYGB)

RYGB is a complex procedure both anatomically and physiologically.  There are several mechanisms of action involved. First, there is early satiation after eating a small amount of food due to the small volume and slow emptying of the gastric pouch. The small stoma provides a restrictive component through delayed gastric emptying. The diversion of food away from the distal stomach, duodenum and proximal jejunum reduces the digestion and possibly the absorption of food by this area of the gut. However, as most of the small bowel remains in the absorptive pathway, it is unlikely the absorption of macronutrients is affected and so the standard RYGB should not be regarded as having a malabsorptive component. The long-limb version of RYGB where food is diverted from the digestive enzymes of the pancreas for 150cm or more₃₉ is more likely to contain an malabsorptive component. Micronutrients which are normally absorbed in the upper gut, such as calcium, are changed. Finally it can have an aversion effect with the symptoms of dumping syndrome occurring if there is ingestion of simple sugars or small osmotically-active molecules, leading to reduce sweet-eating. The diversion of food from the duodenum and proximal jejunum may mediate gut hormonal effects with increased release of GLP-1 and GIP from the distal gut. These hormones act as incretins, increasing release of insulin from  pancreatic β cells.

3. Mechanisms in Sleeve Gastrectomy (SG)

Although primarily seen as a gastric restrictive procedure, there are suggestions that the near total gastrectomy modifies hormonal response to hunger and food by ghrelin reduction. Further, with rapid gastric emptying the increase of nutrients into the small intestine may lead to change in distal gut hormonal responses. The sleeve gastrectomy is the first element of the duodenal switch variant of the BPD. It has lately become popular as a single procedure because of ease of surgery, early effectiveness and perceived lack of need for close follow up ("sleeve and leave"). 

4. Mechanisms in Biliopancreatic bypass (BPD)

The initial element of the BPD is a partial gastrectomy either as a standard Bilroth II procedure for the standard BPD or as a sleeve gastrectomy in the DS variant of the BPD. The gastric volume is reduced to 200 -500ml thus limiting food intake and this is considered to be the initial mechanism of effect₄₀.  Subsequently the separation of ingested food from the digestive enzymes until the last 50 cm of terminal ileum leads to malabsorption  of all macronutrients. A number of positive and negative secondary effects occur. Through interruption of the enterohepatic circulation of bile and the bypassing of the proximal small intestine, there is a marked reduction of total cholesterol, triglycerides and LDL-cholesterol. Insulin sensitivity, as measured by HOMA, is improved₄₁.  Malabsorption of amino acids can lead to hypoproteinemia. Malabsorption of micronutrients and minerals can lead to osteoporosis and anaemia.

Outcome from bariatric surgery

1. Mortality and adverse events

Perioperative mortality  There is a mortality risk with any surgery and this risk was strongly evident for bariatric surgery prior to the general use of laparoscopic approach. Pories et al reported a perioperative mortality of 1.9% of the 605 patients treated by open gastric bypass. In a major series from Richmond, Virginia there were 31 perioperative deaths (1.5%) in 2011 patients having RYGB between 1992 and 2004.  The mortality occurring at the level of community surgery is probably higher than from the major academic centers.  Flum and Dellinger used the Washington State Comprehensive Hospital Abstract Reporting System database and the Vital Statistics database to evaluated 30 day mortality of all people having a RYGB procedure in that state during the period 1987 to 2001. Of 3,328 procedures there were 64 deaths, a mortality rate of 1.9%. This period included both laparoscopic and open surgery and could be seen to reflect community practice.
The overall mortality has decreased in more recent years, particularly with the widespread use of a laparoscopic surgical approach as reported in the systematic reviews of the published data . Death after LAGB is rare and in most reports is 10-15 times less likely than after RYGB₄₂, ₄₃ . At the Centre for Bariatric Surgery in Melbourne, we have performed more than 6000 primary LAGB procedures and have preformed revisional LAGB surgery on more than 1500 of these or other patients without any 30-day mortality or any later death related to the LAGB procedure.
The most definitive evaluation of mortality currently available is derived from the Longitudinal Assessment of Bariatric Surgery (LABS) study report in 2009₄₄. This NIH-sponsored study of bariatric surgery involved 10 sites, carefully selected for their expertise and experience.  The 30-day rate of death was  monitored closely. There  were 4776 patients who had RYGB (N=3412) , LAGB (N=1198) or other procedures unspecified in the report (N=166). There were 15 deaths in the RYGB group, 6 after a laparoscopic approach and 9 after an open approach. There were no deaths in the LAGB group of patients. The difference was highly significant.
Early adverse events. The LABS study serves also to inform on early adverse events for the two major bariatric procedures of RYGB and LAGB. Not surprisingly, the incidence of adverse events mirrored the perioperative mortality rates. Using a composite end-point of death, DVT or pulmonary embolism, reintervention or failure to be discharged by 30 days, they identified 189 who were positive to that end-point, 177 in the RYGB group (5.2%) and 12 in the LAGB group (1.0%), a difference that was highly significant. The complication rate for sleeve gastrectomy is at least comparable to RYGB.  In the systematic review of all reports available on the sleeve gastrectomy reported by Brethauer in 2009₄₅, the quality of the data prevented careful analysis but those papers that included complications declared rates from 0% to 24%. Postoperative leaks from the staple line after sleeve gastrectomy are relatively frequent (2-3%) and appear to be independent of surgeon experience₄₆. In contrast to leaks after RYGB, they tend to be slow to close thereby generating greater morbidity, anxiety and costs.
Late adverse events. There is, and always will be, a maintenance requirement with any bariatric procedure as we are treating a chronic disease. The procedure needs to remain effective over decades rather than years. It is inevitable that there will be the need to correct or repair.  Whilst reversal of a bariatric procedure should be counted as failure, revision to correct or repair should not.  It is a part of the process of care. 
All bariatric procedures have been shown to have a maintenance requirement. The revisional surgery rate of the studies shown in table 3 had a median of 24%  and it was not different between procedures. The median rate for the six RYGB reports that provided data was 22% with a range of 8% - 38%. All of the LAGB sets provided data on revisional surgery. The median value was 26% with a range of 8% - 60%. As almost no details of the type of revisional procedures were provided and, as there were too few reports at ten years on other procedures,  a more detailed analysis is not possible.  

2. Weight Loss Outcomes

Weight loss can be described in different ways, each of which has its advantages and drawbacks. In bariatric surgery the percent of excess weight lost (%EWL) is the preferred method. The excess weight approximates the excess fat within the body. That is what we are trying to reduce and therefore a measure of that effect has more relevance in this clinical setting than measures of total weight change as are commonly used in the non-surgical weight loss literature. It could be argued that percent of excess BMI lost (%EBL) is the most relevant to health status. However as it has a fixed linear relationship to %EWL and it currently lacks broad usage, it has not yet been embraced. Most reports in the bariatric surgical literature provide %EWL, and thus allow comparison between studies.
As obesity is a chronic disease, for treatments to be effective they must also be effective in the long term. Short-term studies (1 - 3 years) are plentiful but simply suggest a  potential effectiveness. Medium term studies (3 -10 years) are far fewer but are more assuring of real effectiveness. Long-term studies (greater than 10 years) are very few and yet are the only ones that truly enable rational decision making on effectiveness. There have been a number of systematic reviews bringing these data together. These provide perhaps the best understanding available of the reasonable weight loss expectations for bariatric surgery in general and for specific bariatric procedures. I will deal with these in order of the duration of follow up provided.
One year outcomes: The most quoted of all the systematic reviews is the report by Buchwald et al₄₇ published in JAMA in 2004. There was 47.5%EWL at one year after LAGB, 61.6%EWL for RYGB, 68.2%EWL for gastroplasty, principally vertical banded gastroplasty, and 70.1%EWL for biliopancreatic diversion. In dealing with the outcome data with one year follow up only, the study gave advantage to the stapling procedures as the weight loss generally peaks at this time for these procedures. However, for the LAGB procedures,  weight loss continues for 2 -3 years and therefore assessment at one year was premature. Note that in this review gastroplasty, a procedure now largely discontinued, appeared to provide  better weight loss than RYGB and was equivalent to BPD in this study.
Short-term (1 - 3 yr)outcomes: Chapman et al₄₂ performed a systematic review of the literature available up to mid-2001 and compared the published reports on LAGB, RYGB and VBG. They found that, although LAGB showed less weight loss at 1 and 2 years,  all three groups of procedures produced comparable weight loss at 3-4 years, that being the longest follow up available on LAGB at that time. They noted the lower mortality associated with LAGB.
Maggard et al₄₃ reviewed the literature up to mid-2003 and identified  89 reports that provided weight loss data after bariatric surgery. Weight loss data were available at or beyond three years in 57 of these reports. Table 2 shows a summary of their weight loss findings for 3 or more years of follow up. 

Based on the confidence intervals, only BPD appears to offer better weight loss than the other procedures.
Medium-term (3 - 10 year)outcomes:   A single systematic review has focused on the medium term-term outcomes and thus included only reports that provided at least three year data₄₈.  A total of 43 reports were included, 18 related to LAGB, 18 related to RYGB and 7 on BPD or its DS variant. Figure 10 shows the %EWL for these three procedures.

Figure 10. The pattern of weight loss over time  after RYGB, LAGB and BPD ( from reference 47, with permission).

The most significant single finding was that each of these procedures was effective in achieving substantial weight loss over the medium term. RYGB was significantly more effective than LAGB at years 1 and 2 but not beyond that point. BPD appeared to be more effective than the other procedures but the difference was shown to be statistically significant at 5 years follow up alone.
Long-term ( >10 year) outcomes:  There have been no published systematic reviews of the long-term outcome of bariatric surgery to date. The following  table provides a summary of the weight data available currently for RYGB, LAGB and other procedures.
The median weight loss for the LAGB studies is 48% EWL with a range of 33 - 60%. For RYGB the median is 55% EWL with a range of 27 - 68%. With such an overlap, it is fair to conclude that neither RYGB nor LAGB can be seen to be superior to the other on current data.

The individual studies have numerous deficiencies making it inappropriate to attempt any meta-analysis or to draw any strong conclusions . The data are particularly vulnerable to bias through poor data management and incomplete follow up, especially as loss to follow up is more likely occur for those who are doing badly. Small numbers of patients at final follow up, such as the 10 patients present for both the Pories study₄₉ and the SOS study₅₀,  is a further notable weakness as evidenced by the wide confidence intervals present in the SOS paper.
Sleeve gastrectomy and gastric imbrication outcomes.
 There are no long -term data on outcomes after sleeve gastrectomy and there are few medium-term data. Brethauer et al provided a literature review of the 36 published reports involving 2570 patients that were available in 2009₄₅. Only one report gave data beyond 3 years. There was a mean weight loss for the full group of 55%EWL . The only study exceeding three years showed a weight regain of approximately 40% from 3 - 5 years₅₁.  Prof Weiner from Frankfurt has the largest series with longer follow up₅₂. He has reported the outcomes  of 746 patients with up to 8 year follow up. The %EWL was 59% at 2 yr, 45% at 5 yr and 36% at 8 yr.
Gastric imbrication is too new to know much of the benefits or risks. Very few reports of weight loss outcomes are available. Brethauer et al report a 53%EWL in 6 patients at one year₅₃. The anticipated freedom from perioperative complications needs to be shown. Just as with sleeve gastrectomy, there is a high likelihood of failure of initial weight loss or weight regain  in the medium term. It remains an experimental procedure at this time.

2. Changes in Health after Bariatric Surgery

Obesity generates a wide range of illnesses, to the point where it could now reasonably be regarded as the worst pathogen in the Western communities. The following are a summary of the changes in a selection of these comorbidities to illustrate the major health benefits that can be achieved by bariatric surgical procedures. The effects may have been achieved through weight loss per se, or as a result of changes in anatomy and function of the gut.

Type 2 Diabetes

Type 2 diabetes mellitus is the paradigm of an obesity-related illness. Multiple studies have documented the benefit achieved by all the current bariatric procedures₄₉, 54-56 .
A randomized controlled trial of LAGB  versus optimal conventional therapy in recently diagnosed (less than 2 yr) type 2 diabetes showed clear benefit for the surgical approach₅₇. There was remission of diabetes (fasting glucose <7mmol/l, HbA1c < 6.2% while taking no hypoglycemic therapy)  in 73% of the surgical group and 13% of the conventional group. The surgical and conventional groups had lost 20.7% and 1.7% of total weight respectively. There were no serious adverse events in either group.
The relative effectiveness of different bariatric procedures has been subject to considerable debate. RYGB is associated with the incretin effects with increased release of GLP-1 and GIP from the distal gut, increasing β cell function, at least in the short term after the procedure₅₈. However comparison with non-surgical patients taking a diet equivalent to the early post-operative RYGB patient suggests that an improvement in insulin resistance immediately after RYGB is primarily due to caloric restriction, and the enhanced incretin response after RYGB does not improve postprandial glucose homeostasis during this time₅₉.
The effects of bariatric surgery on type 2 diabetes have been subject of 2 systematic reviews₆₀, ₆₁ . Buchwald reported 86% of 1835 patients from multiple case studies showed remission or improved control₆₀. Maggard et al₆₁ reviewed 21 case series and reported a range of 64% - 100% showing remission or improvement. Numerous methodological problems existed in most of the published reports. RCTs constituted very few of the studies, the definition of diabetes and its remission were not adequately described and there was extensive but poorly reported loss to follow up. Nevertheless, there was a trend towards better outcomes for the RYGB patients than the LAGB patients with complete remission reported in 70.1% (95% CI 59 - 83) at more than 2 yr after RYGB and 58.3% (95% CI 42 – 74) after gastric banding. There was a direct relationship between weight loss and remission across the studies.
The improvement in diabetes following weight loss is related to the dual effects of improvement in insulin sensitivity and pancreatic beta-cell function₆₂. As beta-cell function deteriorates progressively over time in those with type 2 diabetes, early weight loss intervention should therefore be a central part of initial therapy in severely obese subjects who develop type 2 diabetes. For obese patients with type 2 diabetes, weight loss provides benefit unequaled by any other therapy, and may prove to be the only therapy that substantially changes the natural history of the disease₄₉, ₆₃ .

Dyslipidemia of obesity

Increased fasting triglyceride and decreased high-density lipoprotein (HDL)-cholesterol concentrations characterize the dyslipidemia of obesity and insulin resistance₆₄. This dyslipidemic pattern is highly atherogenic and the most common pattern associated with coronary artery disease ₆₅. Weight loss surgery produces substantial decreases in fasting triglyceride levels, an elevation of HDL-cholesterol levels to normal, and improved total cholesterol–to–HDL-cholesterol ratio 66-68.  Although elevation of total cholesterol is not  obesity-driven, hypercholesterolemia can be controlled by malabsorptive procedures such as BPD₆₉ and, to a lesser extent, RYGB₇₀.

Hypertension

There is evidence of a reduction in both systolic and diastolic blood pressure (BP) following weight loss in association with a bariatric procedure₇₁. We have studied the outcome of 147 consecutive hypertensive patients at 12 months after LAGB. Preoperatively, only 17 of these patients had BP within the normal range, all on therapy. Hypertension was present in 130 patients preoperatively; 101 of these were taking antihypertensive medications and the remaining 29 were not on therapy. Mean BP for these patients was 156/97 mm Hg prior to surgery. At 12 months after LAGB, 105 patients had normal BP, 42 remained hypertensive, and only 42 were taking any antihypertensive medication at that time. Mean BP was 127/76 mm Hg. From these data, we found that 80 patients (55%) had resolution of the problem (i.e., normal BP and taking no antihypertensive therapy), 45 patients (31%) were improved (less therapy and easier control), and 22 patients (15%) were unchanged₇₂. We have demonstrated that the fall in blood pressure is sustained to at least 4-years after surgery but durability of blood pressure reduction over a longer period is uncertain₇₃.

Gastro esophageal reflux disease (GERD)
GERD is much more common in the obese. The community adult prevalence is estimated to be 8-26%  whereas 39 - 53% of an obese population have been shown to suffer the disease₇₄. The reasons for this increase are still unclear but suggestions include reduced basal pressure at the lower esophageal sphincter, increased transient lower esophageal sphincter relaxations, hiatal hernia and abnormal motility patterns in the esophagus or stomach.  Multiple observational studies of LAGB and RYGB have reported strong benefit with improvement in LES function, reduced acid reflux and a level of symptom relief comparable to standard anti-reflux surgery₇₄, ₇₅ _ENREF_82. However it appears that to date no RCTs have been performed directly comparing the two approaches in a well constructed study. We studied 87 patients who had moderate or severe GERD and have been followed for at least 12 months after LAGB. 73 (89%) have had total resolution of the problem, as defined by the absence of symptoms without treatment for the previous month. Preoperative and postoperative pH study and manometry have been performed on 12 of these patients who had severe symptoms preoperatively. The mean DeMeester score was 38 +/- 15 preoperatively and 7.9 +/- 8 at follow-up (p<0.001). In all but one of these patients symptoms had resolved completely₇₆.

Asthma

There is a positive relationship between asthma and obesity with a possible dose-response effect in evidence₇₇, ₇₈ _ENREF_85. The Nurses' Health study identified a five-fold  increase in the relative risk of asthma with a weight gain of 25kg from age 18 when compared to a weight stable group₇₉_ENREF_86.  In the setting of obesity, asthma is more difficult to control₈₀, ₈₁ .  Weight loss by non-surgical means has shown to improve asthma. In an RCT from Finland₈₂ the weight loss group (14% of total body weight lost) showed  improved lung function, symptoms, morbidity, and health status. However lack of durability of the weight loss programs limits the clinical application of the non-surgical approach.
  Several observational studies have report major improvement in asthma after bariatric surgery. A study of 32 consecutive patient with asthma treated by LAGB  reported improvement in all measured aspects of the disease, including symptoms, severity, need for asthma medications (including corticosteroids), and hospital admissions₈₃. The asthma severity score fell from 44.5 before operation to 14.3 at 12 months after operation. Other studies have also reported benefit after LAGB₈₄ and community studies indicate an important reduction of asthma medications after bariatric surgery in the state of Michigan at a time when RYGB was the dominant procedure ₈₅, ₈₆ . No RCTs of bariatric surgery versus best medical care appear to have been performed to date.

Obstructive sleep apnea

A range of sleep disorders is associated with obesity. The most serious of these is obstructive sleep apnea (OSA). Severe obesity is the greatest risk factor for the development of sleep apnea, with a 10-fold increase in prevalence. Excessive daytime sleepiness, a disabling and potentially dangerous condition, is very common in the obese population and is not necessarily related to OSA₈₇. There are major improvements in sleep quality, excessive daytime sleepiness, snoring, nocturnal choking, and observed OSA with weight loss following LAGB surgery₈₈.
Obstructive sleep apnea and other sleep disturbances have been studied in 313 patients prior to LAGB and repeated at one year after operation in 123 of the patients₈₈. There was a high prevalence of significantly disturbed sleep in both men (59%) and women (45%). Observed sleep apnea was decreased from 33% to 2%, habitual snoring from 82% to 14%, abnormal daytime sleepiness from 39% to 4% and poor sleep quality from 39% to 2%.
Depression
Depression is common in the morbidly obese. Does the presence of obesity cause the person to be depressed or does depression cause the person to eat too much? We have investigated the effect of weight loss induced by LAGB on depression as measured by the Beck Depression Inventory (BDI)₈₉. Preoperative BDI on 487 consecutive patients was a mean of 17.7+/- 9.5, a level within the range for moderate depression. Weight loss was associated with a significant and sustained fall in BDI scores with a mean score of 7.8 +/- 6.5 (N=373) at one year after surgery. By four years after surgery, the 134 patients studied had lost 54% of excess weight and had a BDI of 9.6 +/- 7.7.  Although a small number remained in the major depressive illness category, the shift of the majority to normal values for BDI strongly indicates that most of the depression of obesity is reactive to the problem of obesity rather than a cause of obesity and is resolved by weight loss.

3. Improvement in Quality of Life

Improvement in QOL is one of the most gratifying outcomes of bariatric surgery. A number of studies clearly demonstrate major QOL improvements following bariatric  procedures 90-94.  A large prospective study of QOL after weight loss surgery employed the Medical Outcomes Trust Short Form-36 (SF-36). The SF-36 is a reliable, broadly used instrument that has been validated in obese people. In this study, 459 severely obese subjects had lower scores compared with community normal values for all 8 aspects of QOL measured, especially the physical health scores. Weight loss provided a dramatic and sustained improvement in all measures of the SF-36. Improvement was greater in those with more preoperative disability, and the extent of weight loss was not a good predictor of improved QOL. Mean scores returned to those of community normal values by 1 year after surgery, and remained in the normal range throughout the 4 years of the study. It is significant that patients who required revisional surgery during the follow-up period achieved the same improvement in measures of QOL. Similar improvements in QOL have been demonstrated in patients having LAGB for previously failed gastric stapling₉₅.
Studies of appearance orientation and appearance evaluation indicate that the severely obese usually have quite normal pride and investment in their appearance and presentation but they evaluate their appearance as being very poor₉₆.  Weight loss following LAGB has been shown to produce major improvements in self-evaluation of appearance, although it does not return to community normal levels. The extent of the improvement in appearance is related to the percent of excess weight loss. The discrepancy between one’s pride and investment in appearance and presentation and one’s self evaluation of appearance is lower with weight loss, reducing psychological stress₉₆.

4. Improvement in Survival

The ultimate test of effectiveness of a treatment is the reduction of mortality. A comparison of the long-term mortality of bariatric surgical patients with obese controls shows improved survival. A systematic review by Pontiroli and Morabito₉₇ identified  8 relevant trials, shown in table 4. They  reported a reduction of  risk of global mortality with an odds ratio of 0.55 (95% CI = 0.49 - 0.63) . The overall survival advantage was not different between LAGB (odds ratio 0.57) and RYGB (odds ratio 0.55). 

Table 4. The relative risk of mortality compared to controls after weight loss following bariatric surgery.
Study	Operation	Relative Risk	Source of controls
Christou (2004)98	RYGB	0.11	Medical
Flum (2004)99	RYGB	0.67	Medical
SOS study (2007)50	Various	0.71	Medical
Busetto (2007)100	LAGB	0.38	Medical
Adams (2007)101	RYGB	0.40	Community
Peeters (2007)102	LAGB	0.28	Community

The source of the control patients should be known and considered in the interpretation of the trials as sourcing a control group from a medical setting can preselect those who already have an existing disease that will shorten their life expectancy. As an example, the study by Christou₉₈ used  patients admitted to the Quebec provincial health insurance database with a diagnostic profile which included obesity as their control group. The reasons for admission were not known. This group had a mean age of 47 yr and had a mortality rate of  12.6 deaths per 1000 patient.years.  By comparison, the Peeters' study  (mean age of 55 yr) and Adams study (mean age of 39 yr)  used true community controls and had mortality rates for the controls of 8.6 and 5.7 deaths per 1000 patient.years respectively. Adjusting for age, the mortality rate  for the Christou patients was approximately twice those using community control, suggesting they included a number with late-stage illness
The study by Adams101 had sufficient numbers and details to provide some sub-group analysis. They found that  mortality was significantly reduced for deaths from diabetes, heart disease and cancer whereas the rates of death from accidents and suicide were higher in the surgical group. 
In spite of some weaknesses in the data and the inability to do a matched controlled study,  the consistent pattern of the various reports indicates that global mortality is reduced in association with weight loss after RYGB and LAGB

The Hierarchy of Obesity Therapies

Resolution of the disease of obesity requires substantial and durable weight loss. The therapeutic options available are listed in table 4 in order of their risk, side effects, invasiveness and costs. We should always begin with the simplest and safest and work down the list. Only when a simpler and safer option has failed should we seek a more complex or risky option.

Lifestyle therapies (diet, exercise, behavioral change) should always be the first line of management.  Multiple RCTs have shown that a modest weight loss of between 2 and 5 kg can be achieved at 12 months 103-106 . This level of weight loss is associated with a clinically valuable reduction of metabolic risk 107-109 but generally will not solve the problems of obesity.  Lifestyle therapies should be applied optimally and sought to be maintained permanently. If however they fail to resolve the obese patient’s problems, the next level of therapy should be considered. Current drug therapies add little further benefit 110 . Very low energy diets can be effective if taken correctly but are inevitably short term. The recent versions of the intragastric balloon have yet to show effectiveness by RCT and remain short term options. In spite of vigorous research effort, no additional endoscopic approaches are yet available which can provide even medium term benefit.
In general, this table provides a path along which the obese patient seeking treatment should travel. The procedure of gastric imbrication has not been placed on the list as its safety and effectiveness are not yet known.

Comparison of bariatric surgery with non-surgical therapies

We have performed three randomised controlled trials (RCT) in which we have compared gastric banding with optimal non-surgical programs. The initial RCT was of mild to moderately obese adults (BMI 30-35). We compared optimal non-surgical therapy, including lifestyle measures, drug therapy and very low energy dietswith the gastric band and showed significantly better weight loss, health and quality of life for the banding group 111 .  Adverse events were similar between groups. The gastric band patients had lost 86% of their excess weight (%EWL) compared to 21% EWL in the non-surgical group. This substantial weight loss effect has remained at 6 yr follow up(figure 11).

The gastric banding participants showed almost complete resolution of the metabolic syndrome, from 38% to 3%, (versus 38% to 24%; a non-significant change) and markedly improved quality of life as measured by the SF-36. The second study was of obese adults (BMI 30 – 40) with type 2 diabetes. There was 73% remission rate of diabetes in the gastric band group and 13% in the lifestyle group 57 . Again, the metabolic syndrome was significantly improved in the banding group alone. The third RCT was of obese adolescents (BMI > 35; age 14 -18yr) 113 .  The gastric band group lost 79% of their excess weight and showed a significant improvement on the metabolic syndrome which reduced from 36% to zero. There was also an improved quality of life.

Comparison between bariatric surgical procedures.

Table 5 lists a range of comparators and the position of each current option against these comparators.

Table 5. Comparison of attributes of the principal bariatric procedures
Attribute	LAGB	RYGB	Sleeve Gastrectomy	BPD +/- DS
Safe	+++	++	++	+
Weight loss: 1. Short term 2. Medium term 3. Long term	++ ++ ++	+++ ++ ++	++ Not known Not known	+++ +++ ?+++
Durable	+++	++	Doubtful	+++
Side effects	++	++	+	++
Reversible easily	Yes	No	No	No
Minimally invasive	+++	++	++	+
Controllable/adjustable	Yes	No	No	No
Low revision rate	++	++	?	++
Requires follow up	+++	++	++	++

The key outcome comparators between procedures are weight loss and safety.  Short term data (<3 yr) are largely irrelevant as durability is essential.  Systematic review of the medium term weight loss outcomes have shown no difference between RYGB and LAGB and suggest there is a better weight loss to be achieved with biliopancreatic diversion.  Figure 10 shows the relative % EWL for the three principal procedures. Long term (> 10 years) weight loss as shown in table 3  also appears to be similar for RYGB and LAGB but several studies have a major potential for bias, particularly those with low numbers of patients.

Decision making re surgical options - A personal view

How should the potential patients be advised? The advice  surgeons give to their patients inevitably will reflect their training and experience in the setting of their own particular healthcare system  with its unique funding arrangements. The following is a personal view on the basis of extensive experience with RYGB and other stapling procedures and with LAGB, many years of research into obesity, weight loss and bariatric surgery, broad awareness of the bariatric surgical literature and current clinical activity within the Australian healthcare system and the US healthcare system. 
LAGB is the first option. For our practice at the Centre for Bariatric Surgery  in Australia and at the American Institute of Gastric Banding in Texas, we use the LAGB as our initial option in nearly all patients. When applied properly, it is proven to be effective, safe and gentle. Adjustability permits maintenance of effect as long as the band is in place. Reversibility permits access to other therapeutic options that may be developed in the future. There is a need for long term skilled aftercare and there is a maintenance requirement with approximately 10% needing some revisional procedure during the first 10 years. However we know that removal and replacement of the band for proximal gastric enlargement is effective and the revised patients have a weight loss equal to the total group. 
  
RYGB is not now favoured. RYGB has been known to be the most  effective of the stomach stapling procedures since the 1980s 14 and was a personal preference prior to availability of the LAGB. It achieves good weight loss, particularly in the short term. However it carries significant risk, it is non-adjustable and essentially not reversible. Its effectiveness tends to fade with time.  In the first 12 months after RYGB, an excellent weight loss of 60 -70% EWL can be expected. This effect is  maintained for 12-24 months and then begins a gentle fade to average of 55% EWL for those still attending follow up at 5 yr.  It is very effective in resolving type 2 diabetes, possibly through a post-prandial increase of the incretins GLP-1 and GIP. It is now commonly but not universally performed laparoscopically. The significant mortality of 0.44%  seen in the LABS study involved expert bariatric surgeons 44 . The community mortality rate is likely to be higher. I cannot justify the increased risk, the lack of adjustability or reversibility when I can achieve as good weight loss with the LAGB.
BPD has a small second line role. It is the most metabolically severe of the current options and therefore hasn’t proved to be popular with patients or surgeons in spite of favorable published outcomes.  BPD has been available for 30 years 18 and yet remains a very minor part of bariatric surgery. Worldwide, it constitutes less than 2% of bariatric surgery 26 . However, it does generate good weight loss and should be considered on occasions as a second line bariatric surgical option.
Sleeve gastrectomy is not favoured. The sleeve is the first element of the duodenal switch procedure, a variant of the BPD. It has lately become popular as a single procedure because of ease of surgery, early effectiveness and perceived lack of  need for close follow up.  There is a general expectation that the sleeve will fail to maintain acceptable levels of weight loss in the medium term as the tube of residual stomach inevitably expands. Continuation to completion of the duodenal switch would then need to be considered

Who should be considered and who should not?

1. BMI Criteria
There is level 1 evidence supporting a better outcome for using LAGB in the mild to moderately obese (BMI 30-35) when compared with lifestyle therapy₅₇, 111 . This approach is cost-effective114, 115 . When the two treatment paths are modelled over time, the LAGB approach is dominant i.e. it provides increased number of quality-adjusted life years at a lower cost than the existing option of non-surgical therapies. Any person who is obese (BMI > 30), is suffering from the medical, physical or psychosocial consequences of the obesity and has diligently sought a solution through a range of lifestyle options over time, should be considered for LAGB.
Because the stapling group of  surgical options lack level 1 data, are of greater risk, and are not controllable or reversible, maintenance of existing cut-off of BMI >40 or BMI > 35 with major comorbidities should remain for these procedures.
Age criteria. We now have the results of a RCT showing the clear benefit for LAGB for the obese teenager116 and we offer this option to severely obese teens from age 14 years. We would not countenance offering an irreversible procedure to teens when a safe, effective and reversible option is available.
We are generally hesitant to offer bariatric surgery above the age of 65 but do at least  consider people between age 65 - 70 who do not have chronic cardiovascular or pulmonary disease.
Contraindications.  LAGB  is unsuitable for those who are mentally defective or otherwise unable to engage in the “partnership” needed for optimal outcome. Other contraindications include portal hypertension and remote living which could preclude adequate follow up.

Needs and Challenges

Bariatric surgery is never a quick fix. It is a process of care that begins with a careful initial clinical evaluation and detailed patient education and it continues beyond the operative procedure through a permanent follow up. All procedures have the potential for perioperative complications and death. Revisional surgery is relatively common as maintenance of the correct anatomy is intrinsic to effectiveness. But bariatric surgery does provide a solution to the problem of obesity. It achieves substantial weight loss, improved health and quality of life and a longer life. We need to optimize these benefits and minimize the risks and the costs. The following are some of the areas for further research and development:

• A better understanding of the mechanisms of action of each procedure is required to enable optimum surgery and follow up.
• Accurate and comprehensive data management for all patients. Bariatric surgical procedures should  be incorporated into national clinical registries to enable objective assessment of the risks and benefits across the community. 
• More randomized controlled trials to define the benefits of weight loss on various comorbidities of obesity. More study is needed in particular for the patients with metabolic diseases – type 2 diabetes, metabolic syndrome, non-alcoholic steatohepatitis, the dyslipidaemias, polycystic ovary syndrome and obstructive sleep apnoea.
• Better definition of who is suitable and who is not suitable for bariatric surgery.
• Definition of  safe and efficient pathways for assessment, surgery and aftercare. 
• Cost-effectiveness evaluation of the bariatric surgical approach to disease management in comparison with existing options.
  

Bariatric surgery has the potential to be one of the most important and powerful treatment approaches in medicine. High quality of clinical care, good science and comprehensive data management will allow optimal application of this approach to be realized.