**2.1 Anthropometric (weight loss)**

WL outcomes after bariatric surgery can be expressed as percentage of excess WL (EWL%) or percentage of excess BMI loss (EBMIL%) [1]. Excess weight is 'ideal body weight subtracted from actual body weight' As for the reporting of the duration of follow up, short-term follow-up is defined as <3 years after intervention, medium-term is ≥3 and <5 years after intervention, and long-term is ≥5 years after intervention [1]. The percentage of excess weight loss (EWL%) varies with the follow-up duration. The average expected EWL% post LSG is 50–60% [2]. A study of 12,129 patients found that the mean EWL% was about 60% at 1 year after surgery, and 65% at 2 years [3]. Midterm (3 years) WL outcomes ranged from 46% to 84.5% [4, 5]. Long term (≥5 years) evidence suggests that although patients regain weight after LSG, they still accomplish a "durable" long-term weight. A review of 277 long-term studies that included 2713 patients revealed a mean 58.4%, 59.5%, 56.6%, 56.4%, and 62.5% EWL% at 5, 6, 7, 8, and 11 years, respectively [6].

When comparing WL outcomes of LSG with other restrictive procedure, LSG was a more effective procedure than laparoscopic adjustable gastric banding (LAGB), contributing to greater WL. For instance, in a review of 33 studies (4109 patients), LSG resulted in significantly higher EWL% compared with LAGB, where mean difference was −16.67% at 12 months, −19.63% at 24 months, and −19.28 at 36 months post surgery [7]. Two Large randomized control trails (RCT) assessed the long-term outcomes of LSG and Roux en Y gastric bypass (RYGB), the Swiss Multicenter Bypass or Sleeve Study (SM-BOSS) [8] and the SLEEVPASS [9]. Both studies reported similar EWL% at 5 years in LSG and RYGB (61.1% vs 68.3%) and (49% and 57%) respectively [8, 9].

#### **2.2 Type 2 Diabetes Mellitus**

The improvement in type 2 diabetes mellitus (T2DM) occurs soon after surgery and before considerable WL is achieved, which suggests the existence of weightindependent mechanisms. This is attributed to the changes in the gut hormones, mainly the increase in GLP-1 and the decrease in ghrelin hormone levels post LSG. In the long term, the significant weight loss with LSG leads to improvement in both hepatic and peripheral insulin sensitivity which contributes to T2DM resolution [10]. LSG is associated with significant T2DM improvement. Complete remission rates are 78.3% at 1 year, and 76.2% at 3 years follow up [11]. At 5 years, the remission rate ranged between 60.8% to 71.4% [11, 12].

A body of literature compared the T2DM outcomes of LSG vs conventional medical management [13, 14]. The 5 year outcomes from an RCT (STAMPEDE) that compared intensive medical therapy with BS (LSG or RYGB) found that among 134 individuals, diabetes remission was observed in 5% who received intensive medical therapy alone, compared with 23% who underwent LSG (P = 0.07) [14].

Compared with other restrictive procedures, LSG achieves better T2DM control than LAGB (odds ratio (OR): 0.22, 95% CI: 0.06–0.87, P =0 .03) [7]. LAGB does not cause changes in gut hormones and seem to depend exclusively on restriction for WL and diabetes improvement which might explain the better glycemic control seen after LSG [7]. On the other hand, studies comparing T2DM outcomes between LSG and RYGB reported similar remission rates [8, 9, 15]. A systematic review that included 857 diabetic patients, revealed that T2DM remission rate at 1 year was 63% (LSG) and 74% (RYGB) which were not statistically different [15]. The two RCTs cited previously also confirmed such finding [8, 9].

Several independent factors were identified as predictors of complete T2DM remission, including preoperative HbA1C, EWL%, insulin therapy, age, and oral hypoglycemic medications [11, 16].

#### **2.3 Hypertension and cardiovascular disease**

Hypertension has long been associated with obesity. LSG was found to improve hypertension both in the short and the long term [17, 18]. For some hypertensive patients, blood pressure returned to normal on the first day after LSG with a significant reduction observed within 10 days post LSG [17]. The improvement in the *Laparoscopic Sleeve Gastrectomy: Outcomes, Safety and Complications DOI: http://dx.doi.org/10.5772/intechopen.94534*

blood pressure observed before significant WL suggests other neural and hormonal mechanisms [17]. Over a period of 12 months, hypertension resolved in 87% and improved in 100% of patients [17]. The average number of antihypertensive agents per patient significantly declined from 1.5 to 0.6, and the number of patients requiring >2 antihypertensive agents also fell (baseline 49% vs at 12 months 22%) [17]. On the long-term, hypertension resolved in 62.17% of patients and improved in 35.7% at a mean period of 5.35 years [18]. Moreover, LSG resulted in lower incidence of hypertension on the long term (pre-operative 36.5% vs 14.79% at 5 years), potentially reducing the health system costs [18]. The improvement in hypertension also contributes to a significant 10 year reduction of cardiovascular risk including myocardial infarction and stroke post LSG [19].

#### **2.4 Hyperlipidemia**

Hyperlipidemia is a main comorbidity in severe obesity. LSG regulates lipid markers, with considerable reduction in triglyceride, total cholesterol, very low density lipoprotein (VLDL) cholesterol, and low-density lipoprotein (LDL) cholesterol levels, with increase in high-density lipoprotein (HDL) cholesterol level [20, 21]. At 1-year post LSG, remission of hypercholesterolemia and hypertriglyceridemia was attained in 45% and 86% of the patients respectively [20]. Moreover, the improvement observed led to the discontinuation of medication among 43.7% of the patients [20]. On the long term, LSG showed significant improvement in HDL cholesterol and triglyceride compared with preoperative levels [21]. The decreased LDL cholesterol was significant at 1 year and 3 years post surgery, but the effect at 5 years did not reach statistical significance [21]. Overall complete remission of hypercholesteremia at 1, 3 and 5 years was 40.0%, 45.6%, 26.1% respectively [21]. Hypertriglyceridemia remission rate was 72.2%, 66% and 72.2% at 1, 3 and 5 years respectively [21].
