Researchers at the University of Nebraska Medical Center were part of a large national study that will change how physicians treat small abdominal aortic aneurysms.
Abdominal aortic aneurysms cause swelling or ballooning in the major blood vessel (aorta). They affect about 3% of older Americans, mostly men, and can cause fatal internal bleeding if the aneurysm grows large enough to burst.
Physicians typically monitor the growth of small aneurysms and sometimes have opted to prescribe doxycycline based on previous research suggesting that it reduces inflammation that contributes to aneurysm growth.
But researchers found doxycycline, a commonly used antibiotic, had no beneficial effect compared to a placebo in slowing growth of the aneurysms.
The major finding, published May 26 in the Journal of the American Medical Association, was funded by a $10 million grant by the National Institutes of Health National Institute on Aging.
"It is clear that doxycycline should not be used in patients with small aneurysms to inhibit growth," said Timothy Baxter, M.D., professor and surgeon at UNMC/Nebraska Medicine, who led the study at UNMC and served as chairman of the steering committee/study. "While disappointing, it’s important to know so we don’t subject patients to the side effects of doxycycline when it is not helpful.
"One of the more surprising findings of the study was that the aneurysms in both treatment groups grew at a slower rate than seen in previous studies. We aren’t sure why this is occurring, but it has important implications for how often we re-image abdominal aortic aneurysms for growth and provides a better estimate of when repair might be required."
He said the study also answered the question on whether the side effects of doxycycline, significant for some patients, outweighed what was thought to slow growth of the aneurysm.
A team led by Dr. Baxter and LuAnn Larson, director of UNMC Clinical Research Operations, served as the clinical coordinating center which included setting up 21 clinical sites across the country to recruit patients. Researchers at the University of Maryland School of Medicine also played a major role in the study as the data coordinating center. Other collaborating researchers included individuals from the University of Wisconsin School of Medicine and Public Health and Vanderbilt University School of Medicine.
The JAMA study involved 254 patients with small aneurysms (men 3.5 to 5 cm) and women (3.5 to 4.5 cm) who were randomly assigned to take either 100 milligrams of doxycycline twice daily or a placebo for two years; CT scans were performed at the beginning of the study and on follow-up. Study participants predominately were white and male with an average age of 71 years.
The study can be read at https://jamanetwork.com/journals/jama/article-abstract/2766422.
The National Institutes of Health National Institute on Aging Non-Invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (NTA3CT) commended researchers for the organization and proficiency of the trial, said Timothy Baxter, M.D., who led the study at UNMC.
LuAnn Larson, director of UNMC Clinical Research Operations, said she is not aware of other large or involved studies where UNMC was the national coordinating center for the clinical sites.
"We tracked a lot of information," Larson said. "We tracked the study drug, adverse events, licenses, training and other requirements for FDA compliance. It was fun to be a part of it and when I look back I am proud of the work that was accomplished. It was a good study with good data to base their conclusions on. It was an amazing team that worked well together from all across the country."
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Landmark study shows no benefit of drug to slow growth of aneurysms
