In his research at the University of Texas-Houston Medical Center, Brad Snyder, MD, reviews data on weight loss surgery outcomes every day. When he wanted to isolate the factors leading to success or failure after bariatric surgery, the data led him to an intriguing conclusion. Dr. Snyder recently shared his findings about starting BMIs with OH Magazine.
What sparked your interest in considering starting BMIs in weight loss surgery outcomes, and what did your research uncover?
I wanted to define what might predict a person’s outcome after weight loss surgery. When I looked at the gastric banding patients, one significant difference between those who failed and those who succeeded was their starting BMI. The people who failed to lose more than 15 percent of their excess weight had an average BMI of 49. The people who lost more than 30 percent of their excessive weight at a year out had an average BMI of about 43.
I looked at about 600 gastric band patients a year out from surgery. I stratified their BMIs, charting patients with BMIs in the 30s, the 40s and the 50s while noting their excessive weight loss over a year. It was very clear that people with a BMI of 30 lost considerably more weight over that year than people with BMIs in the 50s.
Were you able to pinpoint a BMI range or a specific BMI in this study?
I was able to be specific to a degree. In extrapolating the data backwards, I came up with a BMI of 46—that is where patients started deviating above or below the mean with respect to their BMI. I then re-assessed the data with this BMI of 46 in mind. I separated the 600 people into two groups: 300 with BMIs less than 46, and 300 with BMIs greater than 46. In comparing the two groups, patients with BMIs less than 46 lost significantly more weight after one month, three months, six months, nine months, and 12 months than all those patients with BMIs greater than 46.
Considering your findings, do you recommend that patients with a BMI over 46 try to get down to that prior to surgery?
No, that might be a lot of weight they would have to lose. At this point in time, if a patient with a BMI of 52 comes in and wants a gastric banding procedure, I’m not going to tell them no. This study does not give us enough information. It’s only a year’s worth of data, so I can only [say] what I found is true up to 12 months.
In these types of studies, it’s important to remember that we’re dealing with averages, not individuals. There are many factors at play—how educated the patient is, how well they understand how the band functions, how motivated they are to embrace proper diet and exercise programs, etc.
In the future, do you expect a patient’s placement in the BMI spectrum to become the primary indicator for success after their specific surgery?
Yes, I do think so. But it’s not going to be just BMI. The goal is to get people healthier. If a patient comes in with a BMI of 60, and I place a gastric band in them and their BMI drops to 50, they might be on significantly less hypertension medication, or may be able to cut back on their diabetic medications. Even by losing that much weight, even though it’s not 50 percent of their excessive weight, it remains a significant amount, and has clinical impact on their comorbidities. I don’t think we’ll get to a point where we say “OK, your BMI is 47 so we can’t do a band on you.” I don’t think that’s where this is headed. This is just starting to give us some insight into how the gastric band works.
So patients should always have the ability to decide between their surgical options?
Yes, definitely. My job as a physician is not to talk a patient into a particular procedure. As a bariatric surgeon, I will offer all procedures available that the FDA has approved for weight loss surgery. That being said, I want to make sure that my patients have realistic expectations for what each procedure will mean for them. If a patient comes in with a BMI of 65 and tells me that they want a gastric band, I want to make sure that I have made it very clear that they should not expect to lose more than 50 percent of their excessive weight. They might, but they shouldn’t expect it.
Are there other notable findings in this paper that you would like to point out?
I stress that what this paper does is examine averages and numbers, not patients. Certainly, highly motivated patients with realistic expectations and good mental and social support are the most successful patients, no matter what their BMI is.
Brad Snyder, MD, is a minimally invasive surgery fellow at University of Texas-Houston Medical Center.
July 2008
Interesting article. I just thought this was a good read.