Bariatric surgery associated with significant reduction in CVD risk in patients with severe obesity

Researchers from the Ohio State University, Columbus, OH, have report that bariatric surgery, compared with nonsurgical care, was associated with significant reduction in cardiovascular disease (CVD) risk in individuals with severe obesity and Nonalcoholic Fatty Liver Disease (NAFLD).

Figure 1: Cumulative Incidence of Composite Cardiovascular Events (CVEs), Primary Composite Cardiovascular Disease (CVD) Outcome, and Secondary Composite CVD Outcome by Bariatric Surgery Status in Adults With Nonalcoholic Fatty Liver Disease and Severe Obesity - Individuals who received nonsurgical care (n = 58 356) and individuals with surgical care (n = 28 608) experienced 7215 and 1568 incidences of CVEs (A), 2401 and 549 incidences of primary composite CVD outcome (B), and 5424 and 1191 incidences of secondary composite CVD outcome (C), respectively. Bariatric surgery status was modeled as a time-varying variable. Survival estimates were obtained using the Simon-Makuch method. The Mantel and Byar test for survival comparisons of data with a time-varying covariate had P < .001 for differences between surgical and nonsurgical groups in all panels.

The authors noted that although bariatric surgery has been associated with long-term improvements in NAFLD histological features and reductions in CVD risk in individuals with obesity, the association between bariatric surgery and CVD risk has not been thoroughly investigated in the full NAFLD spectrum.

To address this gap in the knowledge base, they conducted a large, population-based retrospective cohort study to examine the association between bariatric surgery and CVD risk in individuals with severe obesity and NAFLD. They stated that the findings of this study could help to examine the effectiveness of bariatric surgery in reducing the elevated CVD risk in individuals with severe obesity and NAFLD for whom lifestyle modifications were not sustainable. The main outcome was the incidence of cardiovascular events (CVEs), defined as the first occurrence of either primary or secondary composite CVD outcomes.

Writing in JAMA Network Open, ‘Association of Bariatric Surgery With Cardiovascular Outcomes in Adults With Severe Obesity and Nonalcoholic Fatty Liver Disease’, the study included 86,964 adults (59,773 women [68.7%]). Of these individuals, 30,300 (34.8%) underwent bariatric surgery and 56,664 (65.2%) received nonsurgical care.

The study sample included 11,371 gastric bypasses, 10,404 sleeve gastrectomies and 8,525 other bariatric surgeries. The mean (SD) follow-up time for all participants was 21.1 (20.7) months, with 29.2 (24.6) months for those in the surgical group and 16.8 (16.8) months for those in the nonsurgical group. Compared with those in the nonsurgical group, individuals in the surgical group were younger (43.3 vs 44.9 years; p<0.001), more likely to be women (75.9% vs 64.9%; p<0.001), and less likely to have a history of smoking (6.2% vs 9.4%; p<0.001).

Outcomes

Bariatric surgery was associated with a significantly lower risk of incident CVEs (Figure 1A). At the 96-month follow-up, the surgical group had 1,568 incident CVEs over 57,061.4 person-years, whereas the nonsurgical group had 7,215 CVD cases over 96,150.1 person-years (incidence rate difference, 4.8 [95% CI, 4.5-5.0] per 100 person-years). In the surgical group, the cumulative incidences of CVEs were 5.0% at 24 months, 10.4% at 48 months, 15.6% at 72 months, and 21.6% at 96 months. In the nonsurgical group, the cumulative incidences of CVEs were 12.8% at 24 months, 21.1% at 48 months, 28.2% at 72 months and 35.6% at 96 months.

There were 2,950 primary CVD events, of which 784 followed a secondary CVD event. The risk of the primary incident event was significantly lower in the surgical than in the nonsurgical group (Figure 1B). The incidence rate of the primary outcomes was also lower for individuals with vs without surgery status (absolute rate difference, 15.3 [95% CI, 14.0-16.6] per 1000 person-years). At the 96-month follow-up, bariatric surgery was associated with a 47% lower cumulative incidence of primary events (9.7% for surgical group vs 18.3% for nonsurgical group; aHR, 0.53 [95% CI, 0.48-0.59]) . The hazard of primary CVD outcomes remained significantly lower in individuals in the surgical group after adjusting for secondary events occurring before the primary outcomes (aHR, 0.61; 95% CI, 0.55-0.67).

Bariatric surgery was associated with significantly lower risks of MI, heart failure and ischaemic stroke. At 96 months, the cumulative incidence of MI was 1.7% in the surgical group vs 2.6% in the nonsurgical group, heart failure was 4.2% vs 11.5%, and ischemic stroke was 3.0% vs 3.4%. Similarly, the incidence rates for MI, heart failure, and ischemic stroke were lower in the surgical vs nonsurgical group. Compared with those without surgery status, individuals who underwent surgery had lower adjusted hazards of MI (aHR, 0.80; 95% CI, 0.63-1.00), heart failure (aHR, 0.39; 95% CI, 0.34-0.45), and ischemic stroke (aHR, 0.79; 95% CI, 0.66-0.94).

“The findings provide evidence in support of bariatric surgery as an effective therapeutic tool to lower elevated CVD risk for select individuals with obesity and NAFLD,” the authors conclude. “Although bariatric surgery is a more aggressive approach than lifestyle modifications, it may be associated with other benefits, such as improved quality of life and decreased long-term health care burden.”

Further information

To access this paper, please click here