Omega-loop gastric bypass is more effective for weight loss but negatively impacts liver enzymes: a registry-based comprehensive first-year analysis.

Background: The impact of omega-loop gastric bypass (OLGB) on weight loss and liver enzymes remains inconclusive.

Objective: The aim of this study was to compare the impact of sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and OLGB on weight loss and liver enzyme levels.

Setting: National Bariatric Surgery Registry.

Methods: The study included 10,675 cases of SG, 1590 cases of RYGB, and 469 cases of OLGB that had available baseline and 1-year (12 ± 2 mo) follow-up data.

Results: The highest percentage of excess weight loss was achieved by the OLGB group (84.5% ± 26.7%), followed by the SG (78.5% ± 26.0%) and RYGB (72.0% ± 26.5%) groups (P<.05). The data show that 10% of OLGB cases, 5.2% of RYGB cases, and 1.9% of SG cases (P<.001) had increases in alanine aminotransferase levels, from a normal baseline mean of 23.9 ± 7.5 U/L to an abnormal mean of 64.8.7 ± 66.0 U/L, at follow-up. Similar trends were observed for aspartate aminotransferase and alkaline phosphatase. A regression analysis showed that OLGB was a predictive risk factor for normal baseline alanine aminotransferase levels becoming abnormal postoperatively compared with SG (odds ratio [OR] = 5.65) or RYGB (OR = 2.08) (P<.001). Similarly, OLGB was a predictive risk factor for baseline aspartate aminotransferase and alkaline phosphatase levels becoming abnormal postoperatively. Female sex was the only other meaningful predictive risk of alanine aminotransferase (OR = 2.45) and aspartate aminotransferase (OR = 1.82) becoming abnormal postoperatively.

Conclusion: This study confirmed the strengths of OLGB weight loss outcomes but also demonstrated its negative impact on liver enzymes. Thus, patients and caregivers should be informed of the risks, and close follow-up is warranted.