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Metformin may reduce growth of AAA
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Among veterans with diabetes and asymptomatic abdominal aortic aneurysm, those who had a prescription for metformin had slower AAA growth than those who did not, according to findings in the Journal of Vascular Surgery.
According to the study background, two small trials had found that AAA growth rate was slower in those with diabetes than in those without, but there had not been any population-based studies to investigate the issue.
“To our knowledge, this study is the first to use national [Veterans Affairs] data to examine longitudinal AAA diameter changes and associations within this population of patients,” Ronald L. Dalman, MD, vascular surgeon at Stanford University, said in a press release. “The VA database allows long-term analysis of VA patients nationwide, with follow-up extending to 15 years. The high prevalence of diabetes in the VA population of AAA patients allows analysis of risk factor and demographic influences on AAA enlargement in diabetic patients, a population previously difficult to study.”
The researchers analyzed 13,834 patients with asymptomatic AAA and diabetes (mean age at AAA diagnosis, 70 years; 99% men) documented in the VA health care system between 2003 and 2013. Mean follow-up was 4.2 years.
Among the cohort, 39.7% had a metformin prescription within 6 months of AAA diagnosis.
The researchers performed two analyses, one using multivariate linear regression (model 1 analysis) and one using a multivariate mixed-effects model (model 2 analysis).
In the overall cohort, mean AAA growth rate was 1.4 mm per year in the model 1 analysis and 1.3 mm per year in the model 2 analysis.
In an unadjusted analysis, mean AAA growth rate was 1.2 mm per year in the metformin group and 1.5 mm per year in the non-metformin group (P < .001), according to the researchers.
In the model 1 analysis, metformin prescription was associated with a reduced yearly AAA growth rate of –0.23 mm (95% CI, –0.31 to –0.16), and in the model 2 analysis, metformin prescription conferred a reduced yearly AAA growth rate of –0.2 mm (95% CI, –0.26 to –0.14).
The results were similar when the analysis was restricted to the 7,462 patients with AAA size 35 mm to 49 mm (metformin, 1.4 mm per year; non-metformin, 1.7 mm per year; P < .001).
Elevated yearly AAA growth rate was predicted by the following patient factors: baseline AAA size, metastatic solid tumors, active smoking, chronic obstructive pulmonary disease and chronic kidney disease (P .021 for all). Aside from metformin, decreased yearly AAA growth rate was associated with the following factors: prescriptions for angiotensin II receptor blockers, prescriptions for sulfonylureas and presence of diabetes-related complications (P .002 for all).
“Prospective testing is needed to validate the efficacy of metformin in limiting AAA disease progression in patients regardless of glycometabolic status,” Dalman said in the release. – by Erik Swain
Disclosures: The authors report no relevant financial disclosures.
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