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SM-BOSS outcomes

LSG vs LRYGB equally efficient regarding weight loss

Study also find little difference in quality of life, and complications, although LYRGB more beneficial for GERD

The three-year outcomes from the Swiss Multicenter Bypass Or Sleeve Study (SM-BOSS}’ have reported that laparoscopic sleeve gastrectomy (LSG) and laparoscopic gastric bypass (LRYGB) were “equally efficient regarding weight loss, quality of life, and complications up to three years post-surgery.” The outcomes, ‘Laparoscopic Sleeve Gastrectomy Versus Roux-Y-Gastric Bypass for Morbid Obesity3-Year Outcomes of the Prospective Randomized Swiss Multicenter Bypass Or Sleeve Study (SM-BOSS)’, were published in the Annals of Surgery.

The SM-BOSS is the first, prospective randomised trial comparing outcomes of LSG to LRYGB with an adequate number of patients and a nearly complete follow-up rate of 97% after 3 years. In total, 217 morbidly obese patients (LSG, n=107; LRYGB, n=110) with BMI>40 or >35 with the presence of at least one comorbidity, and failure of conservative treatment over two years, were included in the study.

“These results demonstrate the need for life-long vitamin supplementation and monitoring of deficiencies following LSG and LRYGB.”

The primary end point of the study was weight loss defined by excessive BMI loss (EBMIL) over a period of five years, and the secondary end points were the rate of perioperative and long-term morbidity and mortality, the remission rates of the associated comorbidities, the change in quality of life, and metabolic effects in subgroup analyses.

Outcomes

After three years, six patients were lost to follow-up: in the LRYGB group one patient died within 30 days, another died due to lymphoma 2.5 years postop, two patients moved away; in the LSG group, two patients moved away. The remaining 211 patients (97.2%) were evaluated in the three-year assessment of efficacy and safety. There were no significant differences between the study groups at baseline. Analysis was performed on the intention-to-treat population, as a result the two patients in the LSG group who were converted to LRYGB remained in the LSG group for analysis.

The investigators report that body weight and BMI significantly decreased for both treatments from baseline compared with one, two, and three years post-op (p<0.001). In the LRYGB group, weight increased slightly but significantly from year two to year three (p=0.01) and in both treatment groups, BMI increased slightly but significantly from year two to year three (p=0.01).

There were no significant differences between the treatments in BMI loss or weight loss. The reduction in body weight expressed as EBMIL (Figure 1) was also similar between LSG and LRYGB at each time point (at one year: 72.3 ± 21.9% vs. 76.6 ± 20.9%, p=0.139; at two years: 74.7 ± 29.8% vs. 77.7 ± 30%, p=0.513; and at three years: 70.9 ± 23.8% vs. 73.8 ± 23.3%, p=0.316).

Figure 1: Weight loss: BMI and EBMIL, BMI significantly decreased for both treatments from baseline at all 3 years postop (p<0.001). In both treatment groups, BMI increased slightly but significantly from year two to year three (p=0.01). There were no statistically significant differences between the two groups. EBMIL was also similar between LSG and LRYGB at each time point (at one year: 72 ± 22% in LSG group vs. 75 ± 22% in LRYGB group, p=0.14; at two years: 75 ± 30% vs. 78 ± 30%, p=0.51; and at three years: 71 ± 24% vs. 73 ± 23%, p=0.29 respectively). Scatter plot: red dots: LSG, blue triangles: LRYGB

The percentage of patients with EBMIL >50% was 80% in the LSG and 85% in the LRYGB group, and EBMIL >75% was observed in 46% of LSG patients and 50% of patients in the LRYGB group. There was no statistically significant difference between the two treatments.

After three years, comorbidities (glycemic control, hypertension, OSAS, arthralgia, depression, and hyperuricemia) improved significantly after both procedures with no statistically significant difference between the two procedures. In contrast, GERD and dyslipidemia were better treated with LRYGB

At baseline, 24% of LSG and 26% of LRYGB patients had type 2 diabetes, of which 23% in the LSG group and 21% in the LRYGB group were insulin-dependent, respectively. After three years, complete remission was seen in 60% of LSG patients and in 77% of LRYGB patients (p=0.23).

At baseline, 67% of the LSG patients and 51% of the LRYGB patients suffered from dyslipidemia. After three years, complete remission rate was 44% in LSG and 72% in LRYGB (p=0.008). Significant improvement was seen in both groups; however, the rate of decline of total cholesterol and LDL was significantly higher in the LRYGB group compared with LSG, adjusted for baseline values.

At baseline, 44% had GERD in the LSG group, and 46% in the LRYGB group. After three years, in the LSG group, 61% experienced remission, 5% symptoms improved; in 15% symptoms were unchanged and in 20% worsened.

In the LRYGB group, 78% experienced remission, in 14% symptoms improved; in 6% symptoms were unchanged and in 2% worsened. At three years, the difference in remission rate between the groups did not reach significance (p=0.09), but worsening of symptoms was more often seen in the LSG group (p=0.01). In addition, of the 66 LSG patients with no GERD at baseline, 18% developed de novo GERD symptoms whereas this was only seen in 2% of LRYGB patients (p=0.002).

Assessment of GIQLI (Gastrointestinal Quality of Life Index) and BAROS (Bariatric Analysis and Reporting Outcome System) quality of life (QoL) scores at two and three years demonstrates that patients experience a significant and sustainable improvement in quality of life compared with baseline with a slight decrease between years two and three – with no statistically significant difference between the two groups at any time point.

Surgical interventions

Additional surgical interventions were required in nine patients in the LSG group and in 16 patients in the LRYGB group from postoperative day 30 until the three-year follow-up (8% vs. 15%, p=0.15). In the LSG group, there were two patients converted to bypass due to severe GERD, four patients needed cholecystectomy due to newly developed, symptomatic gallstones, two patients suffered from insufficient weight loss and one patient had an umbilical hernia repair. In the LRYGB group six patients required cholecystectomy, two had a small bowel obstruction, three patients were treated for internal hernia by laparoscopy, in one patient a Fobi-ring was inserted to increase weight loss by adding restriction.

There was no statistically significant difference in complications treated conservatively such as peptic ulcer, stricture, kidney stones, and micronutrient deficiencies between the two groups was found (Table 1).

Table 1: Complications (one month to three years)

The authors acknowledge that although no statistically significant difference in resolution of T2DM and amelioration of glycaemic control could be shown, it should be noted that the SM-BOSS trial is not powered enough for this end-point.

“In the present study, we found no difference in vitamin deficiencies between the 2 groups, which is in contradiction to a previously conducted retrospective analysis, where we found a lower deficiency rate following LSG,” they write. “Both groups had a rather high rate of deficiencies despite regular vitamin supplementation in all patients...These results demonstrate the need for life-long vitamin supplementation and monitoring of deficiencies following LSG and LRYGB.”

“In our opinion, patients with pre-existing symptomatic GERD despite medication, or patients successfully treated with PPIs but refusing long-term acid-inhibitory medication, large hiatal hernia (para-oesophageal hernia or axial hernia >4 cm), and severe gastroesophageal motility disorders are better treated with a LRYGB procedure,” the authors conclude. “Concerning dyslipidaemia, no conclusions can be drawn at this moment. However, LRYGB might be a better choice in patients with additional cardiovascular risk factors such as history of cardio-vascular event, smoking, arterial hypertension, or inherited predisposition for cardio-vascular disease.”

The study was funded by the Swiss National Science Foundation and Ethicon Endo Surgery.

To access this paper, please click here

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