Long-Term Weight Loss and Metabolic Outcomes After Bariatric Surgery in a Large Asian Cohort: A Real-World Cohort...

Metabolic-bariatric surgery (MBS) is the most effective treatment for obesity and its associated metabolic complications. Long-term real-world outcome data from Asian populations remain limited, particularly for procedural comparisons and longitudinal metabolic trajectories.

To evaluate weight loss outcomes, metabolic outcomes, and clinical predictors of treatment response following bariatric surgery in a large Asian cohort, with longitudinal follow-up up to five years in a selected subgroup of completers.

This retrospective cohort study analyzed 1,478 adult patients who underwent primary bariatric surgery (laparoscopic sleeve gastrectomy [LSG], Roux-en-Y gastric bypass [RYGB], or one-anastomosis gastric bypass [OAGB]) between 2012 and 2022 at a single tertiary academic center in Malaysia. The primary outcome was percentage total weight loss (%TWL) at 1, 3, and 5 years, analyzed using an available-case approach. Pre-specified attrition analysis compared the characteristics of 5-year completers with non-completers. Secondary outcomes included longitudinal changes in glycated hemoglobin (HbA1c), blood pressure, and LDL cholesterol, with paired and cross-sectional analyses reported separately. Glycaemic outcome thresholds (HbA1c < 6.5% and < 5.7%) were derived from ADA 2021 criteria; formal remission could not be ascertained because antidiabetic medication data were not available. Procedure-specific 1-year metabolic outcomes were evaluated for LSG and RYGB. Multivariable linear regression explored predictors of 1-year %TWL.

Mean %TWL was 20.80 ± 9.71% (n = 917) at 1 year, 25.14 ± 10.30% (n = 349) at 3 years, and 24.52 ± 10.98% (n = 107) at 5 years; the 5-year sample represented 7.2% of the original cohort and was enriched for older patients, those with diabetes and hypertension, and patients with greater 1-year %TWL (25.33% vs. 19.99% in non-completers, p < 0.001), indicating selective retention bias. Among diabetic patients with paired pre-/postoperative HbA1c (n = 35), mean 1-year reduction was 1.01% (p = 0.007); cross-sectional HbA1c among diabetic patients was 5.95 ± 1.08% at 1 year, with 80.9% achieving HbA1c < 6.5% and 47.8% < 5.7%. Significant blood pressure reductions occurred at 1 year in hypertensive patients across both LSG and RYGB subgroups. The regression model was weak (R² = 0.026); pre-existing diabetes (β = -1.83, p = 0.020) and certain non-Malay ethnicity were associated with lower 1-year %TWL as exploratory, hypothesis-generating signals warranting prospective validation. The overall complication rate was 1.7%; OAGB long-term outcomes could not be reliably assessed (5-year n = 3-4).

Bariatric surgery in this large Malaysian cohort produced significant 1-year weight loss with a favorable safety profile. Three- and five-year data, drawn from a selected subgroup of completers and subject to attrition bias, suggest preserved weight loss in those engaged with follow-up but should not be interpreted as population-level durability claims. Diabetes and ethnicity findings from a weak predictive model are hypothesis-generating and require prospective validation.