Association of Bariatric Surgery With Cardiovascular Outcomes in Adults With Severe Obesity and Nonalcoholic Fatty Liver Disease

Abstract

Importance: There are no approved treatments for nonalcoholic fatty liver disease (NAFLD) despite its association with obesity and increased risk of cardiovascular disease (CVD).

Objective: To examine the association between bariatric surgery and CVD risk in individuals with severe obesity and NAFLD.

Design, setting, and participants: This large, population-based retrospective cohort study obtained data from the MarketScan Commercial Claims and Encounters database from January 1, 2007, to December 31, 2017. Participants included insured adults aged 18 to 64 years with NAFLD and severe obesity (body mass index ≥40) without a history of bariatric surgery or CVD before NAFLD diagnosis. Baseline characteristics were balanced between individuals who underwent surgery (surgical group) and those who did not (nonsurgical group) using inverse probability of treatment weighting. Data were analyzed from March 2020 to April 2021.

Exposures: Bariatric surgery (Roux-en-Y gastric bypass, sleeve gastrectomy, and other bariatric procedures) vs nonsurgical care.

Main outcomes and measures: The main outcome was the incidence of cardiovascular events (primary or secondary composite CVD outcomes). The primary composite outcome included myocardial infarction, heart failure, or ischemic stroke, and the secondary composite outcome included secondary ischemic heart events, transient ischemic attack, secondary cerebrovascular events, arterial embolism and thrombosis, or atherosclerosis. Cox proportional hazards regression models with inverse probability treatment weighting were used to examine the associations between bariatric surgery, modeled as time varying, and all outcomes.

Results: The study included 86 964 adults (mean [SD] age, 44.3 [10.9] years; 59 773 women [68.7%]). Of these individuals, 30 300 (34.8%) underwent bariatric surgery and 56 664 (65.2%) received nonsurgical care. All baseline covariates were balanced after applying inverse probability treatment weighting. In the surgical group, 1568 individuals experienced incident cardiovascular events compared with 7215 individuals in the nonsurgical group (incidence rate difference, 4.8 [95% CI, 4.5-5.0] per 100 person-years). At the end of the study, bariatric surgery was associated with a 49% lower risk of CVD (adjusted hazard ratio [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.

Conclusions and relevance: Results of this study suggest that, compared with nonsurgical care, bariatric surgery was associated with significant reduction in CVD risk in individuals with severe obesity and 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.

Figure 2.. Cumulative Incidence of Myocardial Infarction, Heart Failure, and Ischemic Stroke

Bariatric surgery status was modeled as a time-varying variable. Survival estimates were obtained using the Simon-Makuch method. P values were obtained from the Mantel and Byar test for survival comparisons of data with a time-dependent covariate.