Results Summary

What was the research about?

Some people with severe obesity can’t lose enough weight with diet and exercise to improve their health. Two types of surgery can help these people lose weight. Each type has different health risks and lifestyle impacts. For example, after one type of surgery, patients may only be able to eat certain foods or only small amounts of food.

In this study, the research team wanted to learn if a web-based decision aid improved satisfaction and health outcomes for people considering two types of bariatric surgery. Decision aids help people choose between healthcare options based on what’s important to them. In the first part of the study, the team compared patients who used the decision aid with patients who didn’t. In the second part, the team revised the decision aid and tested it again with more patients.

What were the results?

Patients who used the original decision aid and patients who didn’t had similar

  • Satisfaction or regrets with their decision
  • Weight loss
  • Mental well-being
  • Number of health issues related to their weight
  • Overall satisfaction with care

In the second part of the study, patients who used the revised decision aid had fewer regrets about their surgery decision than patients who didn’t use it. Patients who used the revised decision aid said it was more helpful than patients who used the original.

Who was in the study?

The first part of the study included 878 patients considering bariatric surgery at clinics in Michigan. Of these patients, 79 percent were white, 20 percent were black, 3 percent were American Indian or Alaska Native, and 3 percent were another race. The average age was 44, and 80 percent were women.

The second part of the study included 9,294 patients. Of these, 72 percent were white, and 28 percent were nonwhite. The average age was 45, and 84 percent were women.

What did the research team do?

In the first part of the study, the research team assigned patients by chance to use the decision aid or not. To use the decision aid, patients entered personal traits, such as age, weight, and health problems. The decision aid then showed tailored information based on their personal traits about benefits and harms for each type of surgery, such as the amount of weight loss or the chance of having problems. Patients completed surveys before using the decision aid and again 3 and 12 months later.

In the second part of the study, the research team compared a group of patients who used the revised decision aid with a group who didn’t. Patients took the same surveys before using the decision aid and again three months later.

Patients, caregivers, and doctors helped create the decision aid.

What were the limits of the study?

The second part of the study didn’t assign patients by chance to groups. The differences between groups may be due to factors other than the decision aid.

Future research could continue looking at ways to help patients choose a type of bariatric surgery.

How can people use the results?

Doctors can use the results when considering how to support patients making decisions about bariatric surgery.

Final Research Report

View this project's final research report.

Peer-Review Summary

Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also assesses how the project addressed PCORI’s Methodology Standards. During peer review, experts read a draft report of the research and provide comments about the report. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. These reviewers cannot have conflicts of interest with the study.

The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve descriptions of the conduct of the study or to clarify the connection between results and conclusions. Sometimes, awardees revise their draft reports twice or more to address all of the reviewers’ comments. 

Peer reviewers commented and the researchers made changes or provided responses. Those comments and responses included the following:

  • The reviewers disagreed with the report’s initial conclusions that the revised decision tool for bariatric surgery reduced decisional regret in patients deciding among different weight loss options. The reviewers noted that these initial conclusions were not based on the main study, a randomized controlled trial (RCT), but on a comparison of the usual care arm of the RCT against a later survey testing the feasibility of the revised decision aid. In addition, the reviewers noted that the significant amount of missing data in the trial hampered the ability to make any conclusions from the study results. The researchers agreed to qualify their conclusions based on the lack of a formal test of the revised decision aid. However, they also completed propensity score analyses to check for possible selection bias or significant differences between the sample receiving the original decision aid and the sample receiving the revised decision aid that would make these preliminary results more questionable.
  • The reviewers suggested the researchers delete the report’s sentences on disseminating the decision tool since it has yet to demonstrate clear benefits in a RCT. The researchers agreed that additional research is necessary. However, given the positive feedback they had received from patients, patient advisors, surgeons, and others, the researchers plan to disseminate the tool. They explained that they do not make any claims that the tool is effective in any particular domain, but a wide range of people feel that any improvement in patient education and engagement when considering bariatric surgery would be of benefit to patients, providers, and society. The researchers added that a larger RCT may not be feasible for bariatric surgery.
  • The reviewers asked why use of certain aspects of the original decision tool was low, suggesting that low use could be a barrier to widespread dissemination of the tool. The reviewers also asked how long it took for patients to complete the tool. The researchers responded that when they interviewed patients to understand how to revise the tool, patients expressed that they had trouble with information overload. So, the researchers revised the tool to be more streamlined and to present information in a more stepwise way. The researchers added that it was hard to say what amount of time spent with the tool was appropriate or necessary. However, they said they felt it was more beneficial for patients to use the tool for short amounts of time over a longer period of time, including before making a decision about surgery and when adjusting postoperatively.

Conflict of Interest Disclosures

Project Information

Amir A. Ghaferi, MD, MS^
University of Michigan at Ann Arbor
Improving Patient Decisions about Bariatric Surgery

Key Dates

September 2013
December 2020

Study Registration Information

^Nancy Birkmeyer, PhD, was the original principal investigator on this project.


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Last updated: January 25, 2023