Despite solid research showing that bariatric surgery significantly improves outcomes for patients with obesity and Type 2 diabetes, with benefits including reduced cardiovascular morbidity and mortality, few eligible patients choose to undergo weight-loss surgery.
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But that situation may soon be shifting, thanks to a new personalized risk calculator developed by Cleveland Clinic researchers, who introduced the predictive tool at the Obesity Week 2019 international conference.
“Our calculator lets every patient see for him- or herself their own individualized estimates for events including risk of dying, heart attack, stroke, diabetic kidney disease, and heart failure over the next 10 years,” says Digestive Disease & Surgery Institute bariatric surgeon Ali Aminian, MD. “The calculator allows patients with Type 2 diabetes to understand in a personal way how the risks and benefits of surgery compare to medical management. It could be a game-changer.”
Until now, when physicians discussed risks and benefits with patients choosing between standard medical management and weight-loss surgery, they could only offer estimates based on outcomes for large, anonymous groups. The new calculator changes that.
Its predictions for a particular patient are based on data points describing that patient’s degree of obesity, severity of diabetes, and specific cardiovascular risk factors. Using 26 such variables, the machine-learning algorithms calculate the 10-year risk of mortality, heart attack, stroke, heart failure, and diabetic kidney disease for that individual.
May help break down barriers
“A patient can see, for example, that their risk of dying in 10 years would be 7% without the surgery, but with the surgery it would drop to 2%,” says Dr. Aminian, “They can understand the risks and benefits in a way that they couldn’t see before.”
“In the past few years, bariatric surgical procedures have been included in the evidence-based guidelines for management of diabetes in patients with obesity,” says Dr. Aminian. Nonetheless, only 1% of patients eligible for surgical weight-loss procedures have actually undergone them, he explains.
Part of the problem, he says, is that patients lack insurance or that insurers won’t reliably cover the costs. “Another issue, though, is patients not knowing the benefits of the operations,” he says.
A two-part development process
Dr. Aminian and his team developed the risk score calculator in two phases over the course of about two years. The researchers used data drawn from about 14,000 Cleveland Clinic patients with obesity and Type 2 diabetes. A subset of nearly 2,300 underwent bariatric surgery.
“In part one of our work, we showed that bariatric surgery was associated with significant reductions in cardiovascular morbidity and mortality,” he says. Specifically, the 8-year risk of death proved to be 18% for those patients who underwent standard medical management for their diabetes, while for patients who had weight-loss surgery, the risk of death was about 10%.
In September, Dr. Aminian and his research partners presented their part-one findings at the European Society of Cardiology Congress as late-breaking research, which was simultaneously published in JAMA.
“In part two, we went a step further,” Dr. Aminian says. “Using machine-learning algorithms, we identified 26 risk factors for the different outcomes, including risk of dying, in that large group of patients. Based on those risk factors, we created the formulae we needed to develop the calculator.”
The area under the curve of the calculator’s prediction models ranged from 0.66 to 0.81 (1=perfect discrimination, 0.5=chance), with the best discrimination ability for all-cause mortality.
The team’s results were presented as one of the Top 10 studies at the Obesity Week 2019 Congress.
A readily available tool
The risk score calculator will be available to physicians and patients on two different platforms, beginning in November 2019:
The calculator also will be accessible on the website of the American Society for Metabolic and Bariatric Surgery in late 2019. “The society wants to promote this useful, evidence-based tool,” says Dr. Aminian. “They are going to have a page on their website devoted to making the decision between routine medical treatment versus surgery for Type 2 diabetes and they will offer our new tool.”
Since bariatric surgery results in better health outcomes and longer lives for patients with Type 2 diabetes compared with medical management, Dr. Aminian hopes the risk calculator will prompt more of them to choose surgery. “We look forward to this tool having the power to change patients’ perspectives,” he says.