---

Introduction

Obesity rates have risen astronomically in the past decade. From 2009-2014, the prevalence of obese individuals increased by 2% so that in 2014, an astounding 27.7% of the population classified as obese. Obesity is one of the biggest drivers of chronic disease and as such, contributes significantly to both human morbidity and mortality and rising healthcare costs. Obesity is also the second leading cause of preventable death. If obesity rates continue to follow the current trajectory, by 2030, the cost of obesity-related comorbidities will be $66 billion annually [5].

Bariatric surgery is the only proven modality to promote longterm weight loss in morbidly obese patients, and in doing so, also decreases the medical comorbidities that accompany obesity, namely diabetes mellitus, type 2. In light of this data, the National Institute of Health (NIH) issued a statement in 1991 stating that bariatric surgery was the most ideal treatment modality for patients with morbid obesity, defined as a body mass index (BMI) of 35 or higher [6,7].

Today, the sleeve gastrectomy (SG) is one of the surgical options offered to morbidly obese patients. The SG technique has evolved since the 1980s when Hess and Marceau et al. performed a preliminary SG as part of the larger Bilio-Pancreatric Diversion or Duodenal Switch (BPD-DS) procedure and noted significant weight loss in their patients. This discovery paved the way for the SG to be offered to patients undergoing Roux-en-Y Gastric Bypass (RYGB) as a “bridge” procedure. Then, in the early 1990s, with the advent of minimally invasive and laparoscopic surgery, the SG became a stand-alone surgical alternative for patients [8-13].

SG has many favorable attributes when compared to other bariatric surgical procedures and is reported to be associated with few long-term complications. Today, most patients undergoing SG are offered a laparoscopic procedure, which enhances visualization for the surgeon and provides the patient with a less painful postoperative course. The traditional open approach, on the other hand, is associated with a larger incision with difficult and often cumbersome closure and an increased length of stay. With the technological advancement of the da Vinci Robotic Surgical System (Intuitive Surgical, Sunnyvale, CA), some surgeons have adopted the robotic technique, which further improves surgeon visualization, maneuverability, and better triangulation [14]. For these reasons, Robotic Sleeve Gastrectomy (RSG) is gaining popularity in the treatment of morbid obesity in Europe and North America. Nevertheless, some members of the surgical community criticize the RSG, stating that operating with the robot has a steep learning curve, which threatens to compromise patient outcomes [15]. The purpose of the current study is to perform a meta-analysis to compare the clinical safety and efficacy of RSG and LSG.

---

Methods

A search was conducted through the MEDLINE database using PubMed. Our search terms included: (“Gastrectomy/methods”[Mesh] OR “Gastrectomy/therapy”[Mesh])) AND (“Obesity”[Mesh] OR “Obesity, Abdominal”Mesh]). We filtered all articles from 1967 to 2015, selecting only those that contained the key terms “sleeve gastrectomy” and “obesity”. Additional searches were performed using the Google Scholar and Scopus databases. A manual forward and backward search of key relevant bibliographies was also performed. All searches were conducted in October 2014 and again in January 2015. Abstracts were screened to identify studies that included an internal comparison between RSG and LSG and reported on our outcomes of interest: operative time, perioperative bleeding, length of stay, stricture formation, leak rate, and/or mean BMI after one year.

Two investigators performed the search and independently reviewed all selected articles and extracted data according to a prespecified protocol. Discrepancies in coding required a consensus between both investigators to be considered resolved.

Studies were selected based on the following inclusion criteria:

- Report on patients undergoing sleeve gastrectomy in the setting of morbid obesity [16]

- Include only adult patients (18 years and older)- Contain an internal comparison between RSG and LSGoutcomes

- Follow a prospective or retrospective cohort design

- Available in English

- Studies were excluded by any one of the following criteria:

- Non-human patients were included- Only non-surgical treatments were provided

- Meeting abstracts or Letters to the Editor

For all studies, we reported on one or more of the primary outcomes of interest (operative time, perioperative bleeding, length of stay, stricture formation, leak rate and mean BMI after one year). In addition, we extracted study type, year of publication, number of patients, mean patient age and mean preoperative BMI.

A study level meta-analysis was performed. Stata 12 software (StataCorp LP, College Station, TX) was used for all quantitative analyses. We used two different pooled statistics. Relative risk (RR) was determined for categorical outcomes, and standardized mean difference (SMD) was calculated for continuous outcomes.

For continuous variables, we reported the median and interquartile range. We then calculated the standardized mean difference (SMD) and the relative risk (RR) with the corresponding 95% confidence interval and p-value. The SMD is defined as the difference between the mean and standard deviation of the robotic group minus that of laparoscopic group for each study. The SMD was weighted by the sample size of each individual study.

For categorical variables, we first calculated the degree of heterogeneity across the studies and tested its significance using both Cochrane Q-test (significance level < 0.05) and the I squared statistic (> 50%) to determine the underlying statistical model. We calculated the relative risk (RR) of having an event for categorical outcomes using fixed effect model if no heterogeneity was present between studies or the random effects model when heterogeneity in study design was present. The effect size of each study was calculated by subtracting the proportion of affected individuals from those unaffected and dividing by the pooled standard deviation. A risk difference of zero favors the null hypothesis, meaning there is no difference in outcome measures between patients treated with either therapy. Statistically significant differences were considered at the p < 0.05 level.

The search yielded 630 publications of which 44 were fully reviewed and 4 met inclusion and exclusion criteria and were selected for our meta-analysis ( Figure 1).

The characteristics of each selected study are summarized in ( Table 1). Three studies had a prospective design and one study had a retrospective design. Mean patient age for each study ranged from 38-46 years. Four studies comprised 3,599 sleeve gastrectomy cases. The sample size of studies ranged from 48 to 3,282 patients. In total, 280 cases were RSG and 3,319 were LSG. Mean preoperative BMI ranged from 39.4 to 56 kg/m2 and 41.3 to 57 kg/m2 for LSG and RSG, respectively.

Outcomes of each study are documented in ( Table 2), and metaanalysis forest plots are demonstrated in ( Figure 2). Four studies reported operative time. Operative time was significantly greater for patients undergoing RSG (SMD: 0.494; 95% CI: 0.245-0.743; p < 0.01). Four studies reported length of stay. There was no statistically significant difference in length of stay for patient undergoing LSG and RSG (SMD: -0.062; 95% CI: -0.637-0.513; p = 0.833).