Table 1.

Examples of recent long-term studies of bariatric surgery outcomes and their limitations

Study/Lead Author	Study Design	Populations and Procedures	Follow-up Duration	Published Outcomes	Limitations
Swedish Obese Subjects Study/Sjostrom15,17,18,20,22	Prospective observational with matched controls	2010 surgical cases (13% RYGB; 19% banding; 68% VBG) and 2037 matched controls	10 to 20 years depending on the report	Surgery was associated with greater weight loss at 2 years (−23% vs. 0%) and 20 years (−18% vs. −1%)17; Lower overall mortality (HR: 0.71; P=0.001)20; Lower incidence of T2DM (HR: 0.17; P<0.001)22, myocardial infarction (HR: 0.71; P=0.02)17, stroke (HR: 0.66; P=0.008)17, and cancer (in women only; HR: 0.58; P=0.0008)18; and greater remission of T2DM after 2 years [OR for remission: 8.4; P<0.001] and 10 years (OR: 3.5; P<0.001).15	Not randomized; includes mostly procedures (87%) that are no longer in use today; involves patients from a single country with little racial/ethnic diversity
Utah Mortality Study/Adams24	Retrospective observational with matched controls	7,925 RYGB cases and 7,925 weight-matched controls	Mean 7.1 years	40% reduction in all-cause mortality (HR: 0.60; P<0.001) and a 49% and 92% reduction in CV mortality (HR: 0.51; P<0.001) and T2DM mortality (HR: 0.08; P=0.005)	Not randomized; matching based on self-reported height and weight from drivers-license database; includes only RYGB procedures; patients from a single state
Utah Obesity Study/Adams3	Prospective observational with matched controls	400 RYGB cases; 400 bariatric surgery seekers that did not undergo operation (control 1); 400 population-based matched controls (control 2)	6 years	RYGB group lost 27.7% body weight compared to 0.2% weight gain in control group 1, and 0% change in control group 2. T2DM remission in 62% of RYGB patients and only 8% and 6% in each of the control groups (P<0.001), while incident T2DM was observed in 2% of RYGB patients but 17%, 15% of the control groups at 6 years (P<0.001). Surgery associated with greater improvements in blood pressure, cholesterol, and quality of life (P<0.01).	Not randomized; includes only RYGB procedures; patients from a single state
Department of Veterans Affairs/Maciejewski44,45	Retrospective observational with matched controls	847 surgical cases and 847 matched controls	6.7 years	In unadjusted analyses, surgery was associated with reduced mortality (HR: 0.64; 95% CI: 0.51–0.80).45 After propensity-matching patients, bariatric surgery was no longer significantly associated with reduced mortality in unadjusted (HR: 0.83; 95% CI, 0.61–1.14) and time-adjusted (HR: 0.94; 95% CI, 0.64–1.39) Cox regressions.45 Surgery was also not significantly associated with lower health expenditures 3 years after the procedure.44	Not randomized; includes older (mean age 55), primarily male (74%) veterans; mostly RYGB procedures
Longitudinal Assessment of Bariatric Surgery/LABS Consortium38	Prospective observational	2,458 surgical cases (70.7% RYGB; 24.8% AGB; 5% other procedures)	3 years currently (plan for 5 years)	Median percent weight loss 31.5% for RYGB and 15.9% for AGB; T2DM remission in 67.5% of RYGB cases and 28.6% for AGB; Dyslipidemia remission in 61.9% RYGB and 27.1% AGB; HTN remission in 38.2% RYGB and 17.4% AGB. Other procedures not reported	Not randomized; lacks non-surgical control population; primarily RYGB procedures; in-person weight measures available on 66% of RYGB cases and 76% of LAGB cases
HMO Research Network/Arterburn46	Retrospective observational	4,434 RYGB cases with T2DM	Median 3.1 years	68 % (95 % CI: 66 to 70 %) experienced an initial T2DM remission within 5 years after RYGB. Among these, 35.1 % (95 % CI: 32 to 38 %) redeveloped T2DM within 5 years. The median duration of T2DM remission was 8.3 years.	Not randomized; lacks non-surgical control population; only RYGB procedures
Michigan Bariatric Surgery Collaborative/Birkmeyer43	Prospective observational	Varies depending on publication; 8,847 to 35,477	Varies depending on publication; 30-days to 3 years	Complication rates for SG (6.3%) were significantly lower than for RYGB (10.0%, P < 0.0001) but higher than AGB (2.4%, P < 0.0001). Excess body weight loss at 1 year was 13% lower for SG (60%) than for RYGB (69%, P < 0.0001), but was 77% higher for SG than for LAGB (34%, P < 0.0001).	Not randomized; lacks non-surgical control; patients from a single state