A Comparative Analysis of Postoperative Complications and Five-Year Metabolic Outcomes Following Metabolic and Bariatric Surgery in Patients with BMI 50-60 kg/m2 and BMI > 60 kg/m2

Abstract

Background: A topic of debate revolves around performing metabolic and bariatric surgery (MBS) in patients with a BMI greater than 50 and 60 Kg/m². In patients with BMI > 60 Kg/m², technical difficulties may complicate the MBS. This study aims to provide a comprehensive comparison of perioperative morbidity and mortality, weight loss trends, and medium to long-term outcomes following MBS in patients with a BMI ranging from 50 to 60 Kg/m2 and patients with a BMI > 60 Kg/m².

Materials and methods: This cohort study utilized prospectively registered data from the Iran National Obesity Surgery Database (INOSD). Patients aged ≥ 18 years with a body mass index (BMI) ≥ 50 kg/m² who underwent their first metabolic and bariatric surgery (MBS) between March 2016 and January 2023 at a tertiary academic hospital were included, provided they had at least one year of follow-up. Pregnant women post-MBS were excluded. The dataset encompassed demographic information, preoperative clinical assessments, surgical details, complications, and follow-up evaluations at predefined intervals. Study outcomes adhered to international standards, defining suboptimal initial response (SoIR) as %TWL < 20% at two years post-MBS and recurrent weight gain (RWG) as weight regain > 30% of the initial weight loss. Obesity-related condition remission and improvement were assessed per ASMBS criteria. Statistical analyses were conducted using STATA 17 and R 4.3.1. Statistical significance was set at P < 0.05 with 95% confidence intervals.

Results: his study included 1,430 patients with a BMI ≥ 50 kg/m², of whom 13.1% had a BMI ≥ 60 kg/m². The BMI ≥ 60 kg/m² group had a higher proportion of males (39% vs. 29%), younger patients (median age 38 vs. 39 years), and higher prevalence of sleep apnea (32% vs. 22%). The most common procedure was One Anastomosis Gastric Bypass (69%). While ICU admission and 30-day mortality rates were higher in the BMI ≥ 60 kg/m² group, readmission rates and complications were similar between groups. At two years, the BMI ≥ 60 kg/m² group had a lower median %TWL (37% vs. 41%, p < 0.001), but SoIR and RWG rates were comparable. OAGB achieved the highest %TWL and remission of diabetes and dyslipidemia, while RYGB was most effective for hypertension remission. After the first year, weight loss outcomes favored the BMI ≥ 60 kg/m² group.

Conclusions: In conclusion, no statistically significant differences in readmission or complication rates were observed between patients with a BMI of 50-60 kg/m² and those with a BMI >60 kg/m² undergoing MBS. Over a five-year follow-up period, both groups demonstrated similar BMI reduction patterns and similar improvements or remission of obesity-related comorbidities. Among the surgical procedures analyzed, OAGB achieved the highest remission rates for T2DM and dyslipidemia and the greatest TWL% at two years, compared to RYGB and SG.

Keywords: Bariatric surgery; Body mass index; Gastric bypass; Postoperative complications; Weight loss.