Bariatric Surgery Halves Adverse CVD Events in Patients with NAFLD, Severe Obesity

In adults with nonalcoholic fatty liver disease (NAFLD) and morbid obesity, undergoing bariatric surgery was associated with a significantly lower risk for major adverse cardiovascular events than nonsurgical care, according to findings from a large population-based study.

Specifically, investigators from Rutgers University report a nearly 50% reduction in risk for adverse cardiovascular events including myocardial infarction, heart failure, and stroke. Risk was similarly lower for secondary CV outcomes such as ischemic or embolic events, they report in JAMA Network Open.

"The findings provide evidence in support of bariatric surgery as an effective therapeutic tool to lower elevated risk of cardiovascular disease for select individuals with obesity and NAFLD," Vinod K. Rustgi, distinguished professor of medicine, clinical director of hepatology, and director of the Center for Liver Diseases and Liver Masses at Rutgers Robert Wood Johnson Medical School said in a statement from Rutgers. "These finding are tremendously impactful for many reasons."

The progressive increase in incidence of NAFLD in the US is largely driven by steadily rising rates of obesity, metabolic syndrome, and type 2 diabetes. NAFLD prevalence increases with BMI, study authors write, reaching peak prevalence in those with severe obesity (BMI ≥40 kg/m²). Among the population with severe obesity, estimates are that 85% have NAFLD and 40% have nonalcoholic steatohepatitis (NASH), according to the study.

Among the population with severe obesity, estimates are that 85% have NAFLD and 40% have nonalcoholic steatohepatitis (NASH).

Bariatric surgery, the investigators note, is already associated with long-term improvements in histologic features of NAFLD and reduced risk for CVD in persons with NAFLD and obesity, many of whom cannot sustain traditional NAFLD lifestyle interventions targeting weight loss, dietary change, and increased physical activity. What has not been thoroughly investigated, they say, is the association between bariatric surgery and CVD across the spectrum of NAFLD.

Their investigation, a population-based retrospective cohort study of nearly 87 000 adults, was designed to augment this knowledge base which they point out comprises a single small study with only modest results.

For the study cohort, Rustgi and colleagues tapped the MarketScan Commercial Claims and Encounters database between January 2, 2007, and December 31, 2017. A search of the database’s 230 million covered enrollees returned data for 86 964 adults aged 18 to 64 years with NAFLD and severe obesity. Those included had a minimum 12 months of continuous enrollment before the fist NAFLD diagnosis (index date) and severe obesity defined according to clinical guidelines as BMI ≥40 kg/m². Among exclusion criteria were other hepatic disease, excessive alcohol use, previous bariatric surgery, or any of the study’s CVD outcome before the index date.

The outcome of primary interest was the incidence of cardiovascular events, ie, first occurrence of either primary or secondary composite CVD outcomes.

The primary composite CV outcome included MI, HF, or ischemic stroke and the broad secondary composite outcome included either secondary ischemic heart events, transient ischemic attack, secondary cerebrovascular events, arterial embolism and thrombosis, or atherosclerosis. Investigators used Cox proportional hazards regression models with inverse probability treatment weighting to analyze associations between bariatric surgery which was modeled as time varying, and all outcomes.

FINDINGS

The final cohort of 86 964 adults had a mean age of 44.3 years and 68.7% were women. Those who underwent bariatric surgery (surgical group) numbered 30 300 (34.8%) and those who received nonsurgical care (nonsurgical group) numbered 56 664 (65.2%). Bariatric procedures included Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy, and other types of bariatric surgeries. The mean follow-up time for all participants was 21.2 months and was 29.2 months for surgical group patients and 16.8 months for those receiving nonsurgical care.

The investigators recorded 2950 primary CVD events; 784 of those followed a secondary CVD event. At the 96-month follow-up, bariatric surgery was associated with a 47% lower cumulative incidence of primary events (9.7% surgical vs 18.3% nonsurgical; 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)

Analysis of CVD risk found that bariatric surgery was associated with a 49% lower risk of CVD (aHR, 0.51; 95% CI, 0.48-0.54) compared with nonsurgical care. The risk of primary composite CVD outcomes was reduced by 47% (aHR, 0.53 [95% CI, 0.48-0.59), and the risk of secondary composite CVD outcomes decreased by 50% (aHR, 0.50; 95% CI, 0.46-0.53) in individuals with vs without surgery.

The authors point out that interventions that target NAFLD-associated obesity could potentially reduce this population’s risk of CVD but acknowledge that there are no approved medications with this indication; the benefits of lifestyle modifications, they add are difficult to sustain.

“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,” Rustgi said.

Reference: Elsaid MI, Li Y, Bridges JFP, et al. Association of bariatric surgery with cardiovascular outcomes in adults with severe obesity and nonalcoholic fatty liver disease. JAMA Network Open. 2022;5(10):e2235003. doi:10.1001/jamanetworkopen.2022.35003