Chart predicts long-term bariatric outcomes.
"This project was inspired by the utility of pediatric growth charts. They allow monitoring of height and weight for any given age," Dr. Lindsey S. Sharp explained at the annual meeting of the American Society for Metabolic and Bariatric Surgery.
The gastric bypass surgery weight-loss chart can be used to target patients for interventions aimed at boosting their long-term outcomes. The chart was derived through retrospective analysis of prospectively collected data on 1,274 patients who underwent primary Rouxen-Y gastric bypass at Duke University, Durham, N.C., between 2000 and 2007.
The percentage of excess weight loss was determined for each patient at follow-up clinic visits scheduled for 1, 3, 6,12, and 36 months. The purpose was to define the normal pattern of weight loss following gastric bypass, use that information to generate weight-loss nomograms, and then learn whether early weight loss predicts long-term success. It turns out that it does, according to Dr. Sharp of Duke.
According to the chart, a 12%-15% excess weight loss at the 1-month postoperative visit places a patient in the second quartile. The third quartile is a 16%-18% excess weight loss, while more than 18% excess weight loss is the fourth quartile.
At 12-month follow-up, most patients remained in the same weight-loss quartile they were in at 1 month post surgery. Being in the first weight-loss quartile at 1 month, with a 0%-l 1% excess weight loss, had a 39% positive predictive value for being in the first quartile at 12 months. The negative predictive value was 81%. Sixty-one percent of patients in the first quartile at 12 months, with a 15%-53% excess weight loss, were in the first or second quartile at 1 month.
Moreover, 72% of patients in the fourth quartile at 12 months, with a greater than 70% excess weight loss, were in the third or fourth quartile at 1 month. These trends continued at 36 months.
"The take-home message here is that, in general, patients who do well initially are likely to continue along that path, and those who have first-quartile weight loss at the first postoperative visit are at risk of having continued poor weight loss," Dr. Sharp explained.
Further analysis showed that an excess weight-loss velocity of 2% or more per week between the 1--and 3-month postoperative visits had a specificity of 90% for being above the first quartile for excess weight loss at 1 year.
"Our suggested algorithm for follow-up includes assessment of excess weight loss at the first postoperative visit. If patients are found to be in the first quartile, then they should be assessed for dietary, exercise, and psychological factors that could be modified. Frequent follow-up between the first- and third-month postoperative visits can be used to assess the success of the interventions using the excess weight-loss velocity. Hopefully, patients will improve their weight loss. In continuing to follow them, if they again drop down to the first quartile, you can institute new interventions," Dr. Sharp said.
He added that he and his Duke coin-vestigators are designing a structured intervention protocol that includes pharmacotherapy, psychological support, treatment of comorbid anxiety or depression, exercise modification, and dietary management. The efficacy of the protocol will be examined in clinical trials.
Audience members hailed the surgical weight-loss nomograms as "a brilliant concept" and "excellent work," but they wondered whether the charts will perform equally well in their own patients. They noted that the charts were developed at a single center and haven't yet been validated in other populations. Dr. Sharp said that can be accomplished using existing gastric bypass surgery databases.
The charts will eventually be published in the journal Surgery for Obesity and Related Diseases.
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|Publication:||Internal Medicine News|
|Date:||Oct 1, 2009|
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