Cardiovascular disease and mortality in patients with type 2

diabetes after bariatric surgery in Sweden: a nationwide,

matched, observational cohort study

Bj.rn Eliasson, Vasileios Liakopoulos, Stefan Franz.n, Ingmar N.slund, Ann-Marie Svensson, Johan Ottosson, Soffi a Gudbj.rnsdottir

Summary

Background In patients with diabetes and obesity specifi cally, no studies have examined mortality after bariatric

surgery. We did a nationwide study in Sweden to examine risks of cardiovascular disease and mortality in patients

with obesity and diabetes who had undergone bariatric surgery (Roux-en-Y gastric bypass [RYGB]).

Methods In this nationwide, matched, observational cohort study, we merged data for patients who had undergone

RYGB registered in the Scandinavian Obesity Surgery Registry with other national databases, and identifi ed matched

controls (on the basis of sex, age, BMI, and calendar time [year]) who had not undergone bariatric surgery from the

National Diabetes Registry. We assessed risks of cardiovascular disease and death using a Cox proportional-hazards

regression model and other methods to examine the treatment eff ect while accounting for residual confounding.

Primary outcomes were total mortality, cardiovascular death, and fatal or non-fatal myocardial infarction.

Findings Between Jan 1, 2007, and Dec 31, 2014, we obtained data for 6132 patients who had undergone RYGB and

6132 control patients who had not. Median follow-up was 3.5 years (IQR 2.1–4.7). We noted a 58% relative risk

reduction (hazard ratio [HR] 0.42, 95% CI 0.30–0.57; p<0.0001) in overall mortality in the RYGB group compared

with the controls. The risk of fatal or non-fatal myocardial infarction was 49% lower (HR 0.51, 0.29–0.91; p=0.021)

and that of cardiovascular death was 59% lower (0.41, 0.19–0.90; p=0.026) in the RYGB group than in the control

group. 5 year absolute risks of death were 1.8% (95% CI 1.5–2.2) in the RYGB group and 5.8% (5.0–6.8) in the

control group.

Interpretation Our fi ndings provide support for the benefi ts of RYGB surgery for patients with obesity and type 2

diabetes. The causes of these benefi cial eff ects may be the weight reduction per se, changes in physiology and

metabolism, improved care and treatment, improvements in lifestyle and risk factors, or combinations of these

factors.

Funding Swedish Association of Local Authorities and Regions and Region V.stra G.taland.

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