Incidence of type 2 diabetes after gastric by-pass surgery in a Swedish controlled cohort study.

AIMS: To assess the long-term risk of developing type 2 diabetes in patients with obesity who have undergone gastric bypass surgery compared to non-operated patients with obesity and the general population. METHODS: This study included 71,495 patients aged 20-65 years with a principal diagnosis of obesity in the Swedish Patient Register in 2001-2013. Of these, 23,099 had undergone gastric bypass and 32,435 had not. Each patient was matched by age, sex and geographic region with two controls from the general population without obesity diagnosis, i.e., 44,735 controls for the gastric bypass cohort and 62,522 controls for the non-operated cohort with obesity. Operated and non-operated patients with obesity were also directly compared using Cox regression analysis, providing hazard ratios (HR) with 95% confidence intervals (CI) adjusted for age, education, and sex. RESULTS: During a median follow-up of 4.3 years (interquartile range [IQR] 2.4, 7.0 years), 3792 (11.7%) non-operated patients with obesity developed type 2 diabetes (incidence rate 22.8/1000 person-years, 95% CI 22.1-23.6) compared to 394 (1.7%) among gastric bypass patients (incidence rate 4.0/1000 person-years, 95% CI 3.6-4.5). The latter incidence was comparable to population controls (3.5/1000 person-years, 95% CI 3.2-3.8). Gastric bypass patients had 85% lower risk of diabetes compared to non-operated patients with obesity during the first six years of follow-up (HR 0.15; 95% CI 0.13-0.17). CONCLUSION: Gastric bypass surgery for obesity seems to reduce the risk of developing type 2 diabetes to levels similar to that of the general population during the first six years of follow-up but not thereafter.

Surgical treatment of obesity and excess risk of developing heart failure in a controlled cohort study.

AIM: We aim to assess the risk of heart failure in patients with obesity with and without gastric bypass surgery compared with population controls. METHODS AND RESULTS: This cohort study included all patients aged 20-65 years with a first ever registered principal diagnosis of obesity in the Swedish Patient Register in 2001-2013. These patients were matched by age, sex, and region with two population controls from the general Swedish population without obesity diagnosis. The obesity cohort was divided into two groups: 27 882 patients who had undergone gastric bypass surgery within 2 years of obesity diagnosis and 39 564 patients who had not undergone such surgery. These groups were compared with 55 149 and 78 004 matched population controls, respectively. Cox regression provided hazard ratios (HR) with 95% confidence intervals (CI), adjusted for age, education, and sex. During follow-up (maximum 10 years, median 4.4 years, and interquartile range 2.5-7.2 years), 1884 participants were hospitalized for heart failure. Compared with population controls, gastric bypass patients had no excess risk of heart failure during the initial 0-≤4 years of follow-up (HR = 1.35 [95% CI = 0.96-1.91]) but a marked increased risk during the final >4-10 years of follow-up (HR = 3.28 [95% CI = 2.25-4.77]). Non-operated patients with obesity had a marked excess risk of heart failure throughout the study period compared with population controls. CONCLUSIONS: Gastric bypass for obesity seems to reduce the risk of heart failure to levels similar to the general population during the initial 4 years after surgery, but not thereafter.

Prognostic significance of BMI after PCI treatment in ST-elevation myocardial infarction: a cohort study from the Swedish Coronary Angiography and Angioplasty Registry.

BACKGROUND: Obesity along with clustering of cardiovascular risk factors is a promoter for coronary artery disease. On the other hand, a high body mass index (BMI) appears to exert a protective effect with respect to outcomes after a coronary artery event, termed the obesity paradox. METHODS: The Swedish Coronary Angiography and Angioplasty Registry collects information on all patients who undergo percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI) in Sweden along with demographic and procedure-related data. We studied the predictability of four categories of BMI for 1-year all-cause mortality in people with STEMI undergoing PCI. RESULTS: Among 25 384 patients, mean (SD) age 67.7 (12.1) years and 70.2% male, who underwent PCI for STEMI, a total of 5529 (21.8%) died within 1 year. Using normal weight (BMI 18.5-24.9 kg/m2) as a reference, subjects with obesity (BMI ≥30 kg/m2) had a low 1-year all-cause mortality risk in unadjusted analysis, HR 0.59 (95% CI 0.53 to 0.67). However, after adjustment for age, sex and other covariates, the difference became non-significant, HR 0.88 (95% CI 0.75 to 1.02). Patients with overweight (BMI 25.0-29.9 kg/m2) had the lowest 1-year mortality risk in analysis adjusted for age, sex and other covariates, HR 0.87 (95% CI 0.79 to 0.97), whereas those with underweight (BMI <18.5 kg/m2) had the highest mortality in both unadjusted HR 2.22 (95% CI 1.69 to 2.92) and adjusted analysis, HR 1.62 (95% CI 1.18 to 2.23). CONCLUSION: The protective effect of obesity with respect to 1-year mortality after coronary intervention became non-significant after adjusting for age, sex and relevant covariates. Instead, overweight people displayed the lowest risk and underweight individuals the highest risk for adjusted all-cause mortality. TRIAL REGISTRATION NUMBER: NCT02311231.

Heart failure development in obesity: underlying risk factors and mechanistic pathways.

AIMS: People with obesity are at risk for developing heart failure (HF), but little is known about the mechanistic pathways that link obesity with cardiac dysfunction. METHODS AND RESULTS: We included 2030 participants from the Swedish Obese Subjects study who received conventional obesity treatment. First-time detection of HF was obtained by cross-checking the study population with the Swedish National Patient Register and the Swedish Cause of Death Register. We also examined if atrial fibrillation and myocardial infarction as time-dependent variables could predict incident HF The mean age of the study cohort was 48.7 years, and 28% were men. The mean body mass index at baseline was 40.1 kg/m2 and remained stable during a median follow-up of 20.1 years. First-time diagnosis of HF occurred in 266 of patients and was related to male sex, increasing age, greater waist-hip ratio, hypertension, higher cholesterol, diabetes mellitus, and elevated free thyroxine in univariable analysis. Estimated glomerular filtration rate was negatively related to HF risk. In multivariable analysis, atrial fibrillation, which is related to HF with preserved ejection fraction (HFpEF), and myocardial infarction, which is linked to HF with reduced ejection fraction (HFrEF), were strongly associated with incident HF with sub-hazard ratios 3.75 (95% confidence interval: 2.72-5.18, P < 0.001) and 3.68 (95% confidence interval: 2.55-5.30, P < 0.001), respectively. CONCLUSIONS: Both atrial fibrillation and myocardial infarction as time-dependent variables were independently and strongly related to incident HF in people with excess body fat, suggesting two main obesity-related mechanistic pathways leading to either HFpEF or HFrEF.

Surgical obesity treatment and the risk of heart failure.

AIMS: Obesity is associated with increased risk for heart failure. We analysed data from the Swedish Obese Subjects (SOS) study, a prospective matched cohort study, to investigate whether bariatric surgery reduces this risk. METHODS AND RESULTS: From the total SOS population (n = 4047), we identified 4033 obese individuals with no history of heart failure at baseline, of whom 2003 underwent bariatric surgery (surgery group) and 2030 received usual care (control group). First-time principal diagnoses of heart failure were identified by crosschecking the SOS database with the Swedish National Patient Register and the Swedish Cause of Death Register using diagnosis codes. During a median follow-up of 22 years, first-time heart failure occurred in 188 of the participants treated with surgery and in 266 of those receiving usual care. The risk of developing heart failure was lower in the surgery group than in the control group [sub-hazard ratio 0.65, 95% confidence interval (CI) 0.54-0.79; P < 0.001]. After pooling data from the two study groups, the quartile of subjects with the largest weight loss after 1 year (mean -41 kg) displayed the greatest risk reduction (sub-hazard ratio 0.51, 95% CI 0.30-0.70; P < 0.001). This association remained statistically significant after adjustment for surgical intervention and potential baseline confounders (sub-hazard ratio 0.60, 95% CI 0.36-0.97; P = 0.038). CONCLUSION: Compared with usual care, bariatric surgery was associated with reduced risk of heart failure among persons being treated for obesity. The risk of heart failure appeared to decline in parallel with a greater degree of weight loss. CLINICALTRIALS.GOV IDENTIFIER: NCT01479452.

Bariatric Surgery and the Risk of New-Onset Atrial Fibrillation in Swedish Obese Subjects.

BACKGROUND: Obesity is a risk factor for atrial fibrillation, which in turn is associated with stroke, heart failure, and increased all-cause mortality. OBJECTIVES: The authors investigated whether weight loss through bariatric surgery may reduce the risk of new-onset atrial fibrillation. METHODS: SOS (Swedish Obese Subjects) is a prospective matched cohort study conducted at 25 surgical departments and 480 primary healthcare centers in Sweden. The cohort was recruited between 1987 and 2001. Among 4,021 obese individuals with sinus rhythm and no history of atrial fibrillation, 2,000 underwent bariatric surgery (surgery group), and 2,021 matched obese control subjects received usual care (control group). The outcome, first-time atrial fibrillation, was ascertained by crosschecking the SOS database with the Swedish National Patient Register on inpatient and outpatient diagnosis codes. RESULTS: During a median follow-up of 19 years, first time atrial fibrillation occurred in 247 patients (12.4%) in the surgical group, and in 340 (16.8%) control subjects. The risk of developing atrial fibrillation was 29% lower in the surgery group versus the control group (hazard ratio: 0.71; 95% confidence interval: 0.60 to 0.83; p < 0.001). Younger individuals benefited more from surgical intervention than those who were older (p value for interaction 0.001). Also, those with a high diastolic blood pressure benefitted more from surgery than did those with a low diastolic blood pressure (p for interaction = 0.028). CONCLUSIONS: Compared with usual care, weight loss through bariatric surgery reduced the risk of atrial fibrillation among persons being treated for severe obesity. The risk reduction was more apparent in younger people and in those with higher blood pressure.