Health benefits of gastric bypass surgery after 6 years

Abstract

Context: Extreme obesity is associated with health and cardiovascular disease risks. Although gastric bypass surgery induces rapid weight loss and ameliorates many of these risks in the short term, long-term outcomes are uncertain.

Objective: To examine the association of Roux-en-Y gastric bypass (RYGB) surgery with weight loss, diabetes mellitus, and other health risks 6 years after surgery.

Design, setting, and participants: A prospective Utah-based study conducted between July 2000 and June 2011 of 1156 severely obese (body mass index [BMI] ≥ 35) participants aged 18 to 72 years (82% women; mean BMI, 45.9; 95% CI, 31.2-60.6) who sought and received RYGB surgery (n = 418), sought but did not have surgery (n = 417; control group 1), or who were randomly selected from a population-based sample not seeking weight loss surgery (n = 321; control group 2).

Main outcome measures: Weight loss, diabetes, hypertension, dyslipidemia, and health-related quality of life were compared between participants having RYGB surgery and control participants using propensity score adjustment.

Results: Six years after surgery, patients who received RYGB surgery (with 92.6% follow-up) lost 27.7% (95% CI, 26.6%-28.9%) of their initial body weight compared with 0.2% (95% CI, -1.1% to 1.4%) gain in control group 1 and 0% (95% CI, -1.2% to 1.2%) in control group 2. Weight loss maintenance was superior in patients who received RYGB surgery, with 94% (95% CI, 92%-96%) and 76% (95% CI, 72%-81%) of patients receiving RYGB surgery maintaining at least 20% weight loss 2 and 6 years after surgery, respectively. Diabetes remission rates 6 years after surgery were 62% (95% CI, 49%-75%) in the RYGB surgery group, 8% (95% CI, 0%-16%) in control group 1, and 6% (95% CI, 0%-13%) in control group 2, with remission odds ratios (ORs) of 16.5 (95% CI, 4.7-57.6; P < .001) vs control group 1 and 21.5 (95% CI, 5.4-85.6; P < .001) vs control group 2. The incidence of diabetes throughout the course of the study was reduced after RYGB surgery (2%; 95% CI, 0%-4%; vs 17%; 95% CI, 10%-24%; OR, 0.11; 95% CI, 0.04-0.34 compared with control group 1 and 15%; 95% CI, 9%-21%; OR, 0.21; 95% CI, 0.06-0.67 compared with control group 2; both P < .001). The numbers of participants with bariatric surgery-related hospitalizations were 33 (7.9%), 13 (3.9%), and 6 (2.0%) for the RYGB surgery group and 2 control groups, respectively.

Conclusion: Among severely obese patients, compared with nonsurgical control patients, the use of RYGB surgery was associated with higher rates of diabetes remission and lower risk of cardiovascular and other health outcomes over 6 years.

Figure 1. Utah Obesity Study Flow and Follow-Up Over 6 Years

RYGB indicates Roux-en-Y gastric bypass. Recruitment source and follow-up rates are depicted for the RYGB surgery group and comparative control groups. At year 2 examination (35 control participants) and year 5 examination (55 control participants), 101 total control participants had bariatric surgery subsequent to their baseline examination. Follow-up data were collected on all of the control participants who had postbaseline bariatric surgery, with the exception of 2 participants who were lost to follow-up at year 6 examination.

Figure 2. Frequency Distribution of Percentage Weight Change From Baseline to 2-Year and 6-Year Follow-up Examinations

The percentages of participants in the gastric bypass surgery group are shown grouped by 5% of unadjusted baseline weight loss intervals at the 2-year and 6-year follow-up examinations.

Figure 3. Frequency Distribution of Fasting Glucose Measured at Baseline and 2-Year and 5-Year Follow-up Examinations

The percentages of participants in the gastric bypass surgery group are shown grouped by unadjusted fasting glucose intervals of 5 mg/dL (to convert to mmol/L, multiply by 0.055) at baseline and 2-year and 6-year follow-up examinations.

Figure 4. Propensity Score-Adjusted Odds Ratios Comparing Incidence and Remission Rates of Diabetes, Hypertension, and Dyslipidemia Determined at Years 2 and 6 in RYGB Surgery and Control Groups 1 and 2

RYGB indicates Roux-en-Y gastric bypass. Odds ratios are adjusted for a propensity score composed of age, sex, baseline body mass index, income, education level, and marital status (95% Cls are adjusted for multiple comparisons). Clinical end points for both incidence and remission rates were defined as type 2 diabetes (a fasting concentration of blood glucose ≥126 mg/dL, hemoglobin A_1c ≥6.5, or use of antidiabetic medication); hypertension (resting blood pressure ≥140/90 mm Hg or use of antihypertensive medications); and dyslipidemia (a fasting concentration of measured low-density lipoprotein cholesterol [LDL-C] ≥160 mg/dL, high-density lipoprotein cholesterol [HDL-C] <40 mg/dL, or triglycerides ≥200 mg/dL, or use of lipid-lowering medication). No estimate was available for year 2 diabetes incidence (there was no incident diabetes in the RYGB surgery group at 2 years).

Figure 4. Propensity Score-Adjusted Odds Ratios Comparing Incidence and Remission Rates of Diabetes, Hypertension, and Dyslipidemia Determined at Years 2 and 6 in RYGB Surgery and Control Groups 1 and 2

RYGB indicates Roux-en-Y gastric bypass. Odds ratios are adjusted for a propensity score composed of age, sex, baseline body mass index, income, education level, and marital status (95% Cls are adjusted for multiple comparisons). Clinical end points for both incidence and remission rates were defined as type 2 diabetes (a fasting concentration of blood glucose ≥126 mg/dL, hemoglobin A_1c ≥6.5, or use of antidiabetic medication); hypertension (resting blood pressure ≥140/90 mm Hg or use of antihypertensive medications); and dyslipidemia (a fasting concentration of measured low-density lipoprotein cholesterol [LDL-C] ≥160 mg/dL, high-density lipoprotein cholesterol [HDL-C] <40 mg/dL, or triglycerides ≥200 mg/dL, or use of lipid-lowering medication). No estimate was available for year 2 diabetes incidence (there was no incident diabetes in the RYGB surgery group at 2 years).