Bariatric surgery and its impact on cardiovascular disease and mortality: A systematic review and meta-analysis

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Abstract

Background

Bariatric surgery has been shown to improve cardiovascular risk factors but long term benefits for survival and cardiovascular events are still uncertain.

Methods

We searched MEDLINE and EMBASE for parallel group studies that evaluated the clinical outcomes associated with bariatric surgery as compared to non-surgical treatment. Relevant studies were pooled using random effects meta-analysis for risk of myocardial infarction, stroke, cardiovascular events and mortality.

Results

14 studies met the inclusion criteria, which included 29,208 patients who underwent bariatric surgery and 166,200 nonsurgical controls (mean age 48 years, 30% male, follow up period ranged from 2 years to 14.7 years). Four studies were considered at moderate–high risk of bias, whilst ten studies were at moderate or lower risk of bias. Compared to nonsurgical controls there was more than 50% reduction in mortality amongst patients who had bariatric surgery (OR 0.48 95% CI 0.35–0.64, I2 = 86%, 14 studies). In pooled analysis of four studies with adjusted data, bariatric surgery was associated with a significantly reduced risk of composite cardiovascular adverse events (OR 0.54 95% CI 0.41–0.70, I2 = 58%). Bariatric surgery was also associated with significant reduction in specific endpoints of myocardial infarction (OR 0.46 95% CI 0.30–0.69, I2 = 79%, 4 studies) and stroke (OR 0.49 95% CI 0.32–0.75, I2 = 59%, 4 studies).

Conclusions

Data from observational studies indicates that patients undergoing bariatric surgery have a reduced risk of myocardial infarction, stroke, cardiovascular events and mortality compared to non-surgical controls. Future randomized studies should investigate whether these observations are reproduced in a clinical trials setting.

Introduction

Obesity is a worldwide problem with significant consequences on individuals and society. The global age-standardized prevalence of obesity has nearly doubled from 6.4% in 1980 to 12% in 2008 [1]. Obesity is associated with cardiovascular disease, type 2 diabetes, several cancers, diminished average life expectancy, [2] and significant impairments in quality of life [3]. In addition, overweight or obesity in young adulthood and middle age has long-term adverse consequences for health care costs in older age [4]. Whilst people may reduce their weight by dieting, physical activity, behavioral modification or consumption of drugs such as orlistat, many people find it difficult to consistently maintain any reduction in weight [5]. Bariatric surgery is an option that has been shown to be associated with significant weight reduction compared to non-surgical control groups, and potentially confers improvements in disease conditions associated with obesity [6].

The effect of bariatric surgery on a number of endpoints has been extensively studied in the literature. Pontirroli et al. conducted a systematic review and meta-analysis of 8 studies with 44,022 participants and found that compared to controls, surgery was associated with a reduced mortality (OR 0.55 95% CI 0.49–0.63) [7]. Another meta-analysis has shown that bariatric surgery has significant benefits on cardiovascular risk factors including hypertension, diabetes and hyperlipidaemia [8]. In addition, there is evidence to suggest that it results in resolution of major comorbidities including metabolic syndrome, non-alcoholic fatty liver disease, nephropathy, left ventricular hypertrophy and obstructive sleep apnea [9]. However, there has yet to be a systematic review which evaluates the impact of bariatric surgery on cardiovascular events.

In this study, we performed a systematic review and meta-analysis to evaluate the impact of bariatric surgery on long-term incident cardiovascular disease and mortality.

Section snippets

Eligibility criteria

We selected randomized trials and controlled observational studies (cohort design) that evaluated the association of bariatric surgery and clinical outcomes. The following criteria were used for inclusion:

  • 1.

    sample size of > 100 participants undergoing bariatric surgery.

  • 2.

    control group consisting of participants with non-surgical management, either in the same healthcare setting or as community-based controls.

  • 3.

    aimed to evaluate one of the following outcomes: myocardial infarction/ischaemic heart

Results

Our search yielded 2764 potentially relevant articles and after removal of duplicates there were 2295 titles and abstracts, which were screened. There were 30 potentially relevant articles, the full text of these articles was retrieved and 14 studies met the inclusion criteria after full text review [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28]. The process of study selection is shown in Fig. 1.

The available study designs consisted of three prospective

Discussion

This is the first meta-analysis demonstrating that bariatric surgery is associated with a reduced risk of myocardial infarction, stroke and composite adverse cardiovascular events. The reduction in risk of these events was approximately 50% after bariatric surgery compared to non-operated cohorts. In terms of absolute event rates, we found that there were lower fraction of events in the bariatric surgery group compared to non-operated overweight control groups for all outcomes (mortality 3.6%

Conclusions

In conclusion, current observational studies provide consistent evidence that morbidly obese patients undergoing bariatric surgery have lower rates of myocardial infarction, stroke, cardiovascular events and mortality compared to matched non surgical controls (mortality 3.6% vs. 11.4%, cardiovascular events 2.4% vs. 4.0%, myocardial infarction 1.3% vs. 2.5% and stroke 0.8% vs. 1.5%). Whilst, our data does not infer a causal relationship, our analysis suggests that bariatric surgery may be

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    This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation.

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