Bariatric Surgery Cuts CAD in Very Obese, but Do Effects Wane?

Pam Harrison

October 16, 2018

Severely obese patients with diabetes who undergo bariatric surgery are at significantly lower risk for cardiovascular complications over a 5-year follow-up compared with those who receive usual care, a retrospective matched-cohort study indicates.

The researchers specifically studied macrovascular disease, which includes acute myocardial infarction, unstable angina, percutaneous coronary intervention, coronary artery bypass grafting, ischemic and hemorrhagic stroke, carotid stenting, and carotid endarterectomy.

"Macrovascular disease is a leading cause of morbidity and mortality for patients with type 2 diabetes, and medical management, including lifestyle changes, may not be successful at lowering risk," David Fisher, MD, Kaiser Permanente Northern California, Oakland, and colleagues write in their article.

"[We found that] bariatric surgery was associated with a lower risk of macrovascular outcomes, [and] healthcare professionals should engage patients with severe obesity and type 2 diabetes in a shared decision-making conversation about the potential role of bariatric surgery in the prevention of [these] events," the authors advise in their study, published online October 16 in JAMA.

Separately, in another study published in the same issue of JAMA, Wendy King, PhD, University of Pittsburgh, Pennsylvania, and colleagues document the weight regain that can be expected following bariatric surgery in general, describing follow-up of almost 7 years in one particular study. Yet as long as patient expectations are realistic, weight loss surgery is still the best option for patients who are obese, says an accompanying editorial.

Surgical Patients Do Better in Terms of CAD Than Nonsurgery Controls

In the study by Fisher and colleagues, 5301 patients who underwent bariatric surgery between 2005 and 2011 in one of four US integrated healthcare systems were involved. Surgical patients were matched with 14,934 nonsurgical controls.

Slightly over three quarters (76%) of surgical patients had Roux-en-Y gastric bypass (RYGB), 17% had a sleeve gastrectomy, and 7% received an adjustable gastric band.

At the time of surgery, over half of patients (52%) had a body mass index (BMI) between 40.0 to 49.9 kg/m2, the investigators note, and almost half (49%) had had type 2 diabetes for 5 years or more. Median follow-up was 4.7 years for surgical patients and 4.6 years for their nonsurgical controls.

One year after surgery, rates of macrovascular disease were lower among surgical recipients than their nonsurgical counterparts and these differences persisted over the long-term follow-up. Indeed at 5 years, surgical recipients had a 40% lower risk of incident macrovascular events compared with their nonsurgical counterparts, at a hazard ratio (HR) of 0.60.

They also had a 36% lower risk of coronary artery disease (CAD), again at 5 years, compared with patients who did not undergo surgery, at an HR of 0.64.

In contrast, the incidence of cerebrovascular disease was not significantly different between the groups at 5 years.

Cumulative Rates for Macrovascular Disease, Surgery vs No Surgery

  1 year 3 years 5 years 7 years
  Surgery No Surgery Surgery No Surgery Surgery No Surgery Surgery No Surgery
Composite incident
macrovascular disease, %
0.5 1.1 1.1 2.6 2.1 4.3 3.2 6.2
cerebrovascular disease, %
0.3 0.7 0.9 1.8 1.6 2.8 2.3 4.2
Incident CAD, % 0.3 0.7 0.9 1.8 1.6 2.8 2.3 4.2


Surgical Patients Less Likely to Die; Improve Access to Operations

In a post-hoc analysis, Fisher and colleagues also note that mortality rates at all time points were lower for patients who had undergone bariatric surgery compared with those who had not. At 5 years of follow-up, all-cause mortality was 67% lower in favor of surgery compared with nonsurgical controls, at an HR of 0.33.

Commenting on the findings in an accompanying editorial, Adam Sheka, MD, University of Minnesota, Minneapolis, and colleagues, point out that bariatric surgery has long been known to improve microvascular disease.

Now that it has been shown to significantly reduce macrovascular disease events, the question then becomes: "Why is surgery not seen as an alternative to medication for the treatment of type 2 diabetes?"

Clearly, bariatric surgery not only leads to improvements in glycemic control, it has important cardiovascular health benefits as well, Sheka and colleagues argue.

"For prevention of macrovascular events, the societal benefits of aggressive medical therapy for diabetic control are modest and the costs are great," the editorialists stress.

Yet as they acknowledge, access to bariatric surgery is limited and the cost to the patient is often very high.

Thus, "given the benefits of bariatric surgery for patients with type 2 diabetes, including potentially greater long-term benefits than most pharmaceuticals, insurance coverage for weight loss operations should be expanded for appropriate patients," Sheka and colleagues conclude.

Weight Regain After Gastric Bypass a Problem, but Is Surgery Still Best?

If bariatric surgery is arguably the most effective treatment for type 2 diabetes and severe obesity, it nevertheless isn't necessarily universally successful over the longer term, King and colleagues observe in their article.

When weight is regained, obesity-related complications also tend to reappear or progress. This was made apparent in the Longitudinal Assessment of Bariatric Surgery-2 (LABS-2) study of 2458 patients who underwent bariatric surgery between March 2006 and April 2009.

For this particular analysis, King and fellow investigators included 1406 participants who had undergone RYGB surgery. Patients were followed for a minimum of 5 years and had five or more weight measurements over time.

Weight regain following surgery was measured in several ways: weight regain in kilograms from nadir weight (that is, from the largest amount of weight lost post-surgery), BMI,  percentage of maximum weight lost, percentage of pre-surgery weight, and percentage of nadir weight.

The median follow-up from surgery was 6.6 years.

"The median time to reaching nadir weight was 2.0 years after RYGB surgery [and] the median percentage of maximum weight loss was 37.4%," the study authors report. Median BMI at the nadir point of weight loss was 28.8 kg/m2.

The authors note that, at the last assessment, median percentage of weight loss had dropped to 28% while median BMI had risen to 33.2 kg/m2.

However, the propensity to regain clinically meaningful amounts of weight varied, depending on the variable used to measure weight regain.

For example, 5 years after getting to their lowest weight, 43.6% of participants had regained five BMI points or more.

In terms of percentage of nadir weight, 50.2% of participants had regained 15% or more of their nadir weight at 5 years' follow-up, while 86.5% of patients had regained 10% or more of the maximum weight lost, again at 5 years.

The rate of weight regain was greatest during the first year after patients reached their lowest (nadir) weight.

More importantly, 1 year after reaching their lowest weight, 9.9% of patients had evidence of diabetes progression, 25.8% had progression of hyperlipidemia, and 46.2% had worsening hypertension.

There were also "clinically important" declines in physical and mental health in approximately 20% and 28% of patients, respectively. Satisfaction with the surgery also declined in 12.4% of the group overall.

All of these indices continued to deteriorate over the years, with the prevalence of diabetes increasing to 35.3% at 5 years. Again at 5 years, 68.4% and 71.5% of patients had hyperlipidemia and hypertension, respectively.

And significantly more patients, at 42% and 32.8%, reported declines in physical and mental health-related quality of life, respectively, at the same time point, the investigators note.

"All five continuous weight regain measures were significantly related to progression of diabetes, progression of hypertension, decline in physical health-related quality of life, and decline in satisfaction with surgery," King and coauthors observe.

"[However], weight regain quantified as a percentage of maximum weight lost performed better for association with most clinical outcomes than the alternatives examined," they stress.

"These findings may inform standardizing the measurement of weight regain in studies of bariatric surgery," the authors conclude.

Surgery Is Still Best Option, but Set Appropriate Expectations

In an accompanying editorial, Amir Ghaferi, MD, and Oliver Varban, MD, both from the University of Michigan, Ann Arbor, point out that some weight regain after bariatric surgery may not be associated with adverse health consequences, although clinically important amounts of weight regain will be accompanied by the reemergence of comorbid disease.

"For example...a patient with the median baseline weight of the study population of 130 kg (285 lb; BMI, 46.3 kg/m2) would weigh 80.7 kg (178 lb) and have a BMI of 28.7 kg/m2 at the time of reaching nadir weight at 2 years, but at 5 years would weigh 93.9 kg (207 lb) and have a BMI of 33.4 kg/m2," Ghaferi and Varban write.

This finding underscores the importance of clinicians helping patients set appropriate expectations about how much weight they likely will lose following bariatric surgery — and how much they are likely to regain.

And although patients need to anticipate regaining some weight, and perhaps having comorbidities resurface, "bariatric surgery remains the most effective treatment for obesity and its related health conditions," the editorialists emphasize.

"Therefore, it is important for clinicians to understand what to expect from bariatric surgery, provide postoperative care for these patients in a multidisciplinary setting, and manage patient expectations appropriately to ensure the best possible outcomes for patients with obesity," they advise.

Fish, Sheka, and King have reported no relevant financial relationships. Ghaferi and Varban have reported receiving salary support from Blue Cross Blue Shield, Michigan.

JAMA. 2018;320:1570-1582, 1560-1569, 1543-1544, 1545-1547.

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