Types of bariatric surgery
Based on the most recent Australian Bariatric Surgery Registry data, the laparoscopic sleeve gastrectomy (LSG) is the most commonly performed bariatric operation in Australia and accounts for about 70% of surgeries, followed by Roux-en-Y gastric bypass (RYGB) and one anastomosis gastric bypass (OAGB), which together comprise just under 20% of surgeries.2 The popularity of the laparoscopic adjustable gastric banding (LAGB) has significantly reduced, in part related to the substantial need for revisional surgery and the poorer long-term outcomes in the hands of many surgical units, such that it accounts for 2% of bariatric surgical procedures. It is notable that 6% of the bariatric surgery performed in Australia is revisional. These procedures and their effects are described in Figures 1a to c and Table 1. LSG has dominated weight-loss surgeries in both Australia and the US because it is less invasive and more straightforward than gastric bypass with good long-term outcomes. However, bypass procedures appear to have greater metabolic benefits and somewhat more sustained weight loss so are favoured for people with type 2 diabetes.
The OAGB is the newest procedure and has certain advantages over RYGB, such as a single anastomosis, a shorter learning curve for surgeons, fewer defects leading to herniation and easier reversal.3 It is growing in popularity as data is showing outcomes comparable with RYGB.3
Positive effects of bariatric surgery
Compared with conventional treatments, bariatric surgery can produce long-term weight loss that is greater and more sustainable. Data from the large observational Swedish Obese Subjects (SOS) study, published in 2012, showed that bariatric surgery (predominantly the outdated procedure vertical banded gastroplasty [VBG], known as ‘stomach stapling’, that produces a proximal gastric pouch, and which has been largely superseded by the simpler and safer LSG) was associated with greater weight loss than standard care at two years (23% vs 0%) and 20 years (18% vs 1%).4 The prospective Utah Obesity Study demonstrated more effective weight loss for a group of patients undergoing RYGB (27.7%) compared with a nonsurgical control group (0.2% weight gain) after six years of follow up.5 An analysis of UK data has documented four-year weight loss to be 38 kg for RYGB, 31 kg for LSG and 20 kg for LAGB.6 In an Australian study, patients who underwent LAGB were able to maintain more than 50% excess weight loss (defined as the proportion of weight above that which a patient would have at a BMI of 25 kg/m2 that is lost) after more than 10 years of follow up.7 However, in the Longitudinal Assessment of Bariatric Surgery, a multicentre observational study from the US, mean weight loss was 28.4% for RYGB and 14.9% for LAGB seven years after surgery. LAGB was associated with one-third the rate of diabetes remission compared with RYGB (RYGB 60.2% vs LAGB 20.3%).8 There have been two recent randomised controlled trials comparing RYGB with LSG, and although there was greater weight loss with RYGB, this was not statistically significant in either study. At a mean of five years after surgery, RYGB resulted in 68.3% excess weight loss compared with 61.1% for LSG in one study and 57% versus 49% in the other.9,10