About Us

Nationwide, 93 million adults and one in five adolescents have obesity. But the concerns they face go well beyond excess weight. They are at greater risk for heart disease, type 2 diabetes, and cancer, among other health problems.

People with obesity have numerous options to consider when looking for the approach that might work best for them. But for those seeking a surgical solution, finding the right treatment can be as complex as the condition itself.


That’s a challenge that Neely Williams, MDiv, a pastor in Nashville, Tennessee, knows firsthand. She struggled with her weight for 28 years, reaching more than 300 pounds. “The more I weighed, the less I was able to move. And the less I moved, the more I weighed,” she said.

After having weight-loss surgery herself, Williams decided to take action that could help others by becoming the patient co-investigator for a PCORI-funded study of the three most common types of bariatric surgery.

PCORI's Obesity Focus

PCORI supports more than a dozen comparative effectiveness research studies related to obesity. These studies focus on helping patients, their families, and their physicians make better-informed decisions about their healthcare options.

For more information, see our fact sheet, Research Topic page, and a list of our obesity research projects, which focus on treatment, screening, and prevention.

The PCORnet® Bariatric Study was one of the first designed to test the capabilities of PCORnet®, The National Patient-Centered Clinical Research Network, which was developed with PCORI funding. PCORnet securely leverages networks of clinical information from millions of patients to help conduct large-scale health research more efficiently and quickly at a lower cost than would otherwise be possible.

Researchers used data gathered through PCORnet to answer questions about the risks and benefits of the three most common surgical procedures that can help patients with severe obesity—a body mass index of 35 or higher—achieve weight loss not possible with diet and exercise alone.

Thanks to PCORnet, they were able to complete the study in only two years, all while working with patients and other stakeholders who helped shape the study. To learn more about the study, its results and potential value to patients, we spoke with Williams and the study’s principal investigator, David Arterburn, MD, MPH.

Rev. Williams, can you tell us about your personal experience with obesity?

Neely Williams: I started struggling with my weight after my second pregnancy in 1983. For years, I would work to lose weight and then would regain it. You hear about Weight Watchers, you start going to the YMCA to exercise, and you try doing the things that your doctor prescribes. Sure enough, you’ll lose weight. The problem is the minute you stop doing those things, you will regain the weight and it’s usually even more.

It was finally in 2011 that I underwent a Roux-en-Y gastric bypass. The surgery has helped me, but I have also been impacted by many of the post-surgery conditions that I was not aware of until I began working on this study. The study’s results would have been very helpful because I was not sure which procedure was best for me. The only guidance I received was from my surgeon. My pre-surgery screening did not offer details, and I didn’t know what questions to ask.

What makes the PCORnet Bariatric study unique?

David Arterburn: Its size and scope. It is one of the largest bariatrics studies that has long-term, longitudinal outcomes. We were able to report on patient outcomes at five years—pretty unusual in the bariatric surgical space. Most patients do not usually continue to follow up with their bariatric surgeon for five years. It’s also one of the first studies comparing head-to-head the newer sleeve gastrectomy procedure against the longer-standing gastric bypass and adjustable gastric band procedures. We are also unique in the level of patient engagement that we have throughout the whole research process, working with a patient co-principal investigator, other patients as study team members, and a stakeholder advisory group.

PCORnet's infrastructure is a major player behind the scenes that allows for a study like this to happen. It provides a standard data language that allows us to analyze data much more quickly and efficiently than ever before.

David Arterburn, MD, MPH PCORI-funded study Principal Investigator

What made you decide to study adolescents in addition to adults?

David Arterburn: Less is known about adolescents. These procedures are less common and performed on adolescents who are most severely affected by their weight. Adolescents are increasingly facing severe obesity and a higher prevalence of obesity-related health conditions—like early-onset type 2 diabetes—that they’ll likely carry into adulthood. Research provides an opportunity to intervene earlier and reduce the potential complications or severity of diseases. The question is: Which bariatric procedure is the most effective? It’s a complex decision for adolescents and their family members, where they have to weigh the benefits and risks.

What were the results?

David Arterburn: For adolescents, we reported in Surgery for Obesity and Related Diseases that the sleeve gastrectomy performed quite comparably to the gastric bypass through three years after surgery. Adolescents undergoing either one of those procedures experienced greater weight loss compared to adjustable gastric banding. At one year after surgery, adjustable gastric banding showed a 10 percent body mass index loss compared with 31 percent for a Roux-en-Y and 28 percent with the gastric sleeve.

More about the Study

How many records did researchers analyze?

  • 65,000 adult patients and 544 adolescent patients across 41 healthcare systems who underwent one of three bariatric procedures

What procedures were researchers comparing?

  • Roux-en-Y gastric bypass: creation of a smaller pouch from the original stomach that can hold only a small amount of food
  • Adjustable gastric banding: a band placed around the upper part of the stomach
  • Sleeve gastrectomy: removal of a large part of the stomach

All three procedures reduce the amount of food a person can eat before feeling full.

What outcomes were researchers examining?

  • Weight loss at one, three, and five years after each type of procedure
  • Surgical and medical complications 30 days after each procedure

How long did the study take to complete?

  • Two years

At three years after surgery, Roux-en-Y gastric bypass still showed the greatest amount of sustained weight loss. However, when we looked at surgical and medical complications 30 days after each procedure, adjustable gastric banding had the least amount of complications, followed by the sleeve gastrectomy, and then bypass. These findings are similar to those in adults for both the procedures’ associated weight loss and safety.

Adolescents could not be followed through five years because of poor follow-up, but all three procedures in the adult population continued to show similar results in terms of weight loss and safety. At five years in adults, the gastric bypass showed the greatest amount of weight loss but was found to be the least safe. In adults, we also analyzed subgroups of patients. In general, older adult patients, patients with diabetes, and African-American and Hispanic patients, all were groups that tended to lose less weight than populations who were younger, didn’t have diabetes, or who were Caucasian.

How did working with PCORnet contribute to the study?

David Arterburn: PCORnet’s infrastructure is a major player behind the scenes that allows for a study like this to happen. It provides a standard data language that allows us to analyze data much more quickly and efficiently than ever before. PCORnet allowed us to track patients’ electronic health record data over time. Whether they had been seen in the primary care clinic, urgent care, or any other place where they had been touched by the health system, we could capture their weight. Completing a study like this with 41 health systems, bringing together all that data in a two-year timeframe, and answering questions about the efficacy of weight loss, diabetes outcomes, and long-term safety was impossible prior to having PCORnet on the scene.

How did stakeholders impact the project?

David Arterburn: From the outset, patients helped shape the questions that we asked. We included safety as another aim in the study as a direct result of stakeholder feedback, which told us that we cannot only compare the benefits, we also need to compare the risks.

Neely Williams: The researchers involved us throughout the project. They would stop and check in with me to learn more about what mattered most to patients about the project. I was able to call attention to things that may or may not have been considered by the people who were doing the work. I had a lot of opportunities to talk with the researchers about how certain concepts related and to question if they made sense from a patient’s perspective. The researchers and clinicians made changes based on our recommendations. In my experience, research has only had one role for patients in a study: as subjects. In this study, patients were partners in the research process.

What's Happening at PCORI?

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