Yeap, Bu B., Chubb, S.A. Paul, McCaul, Kieran A., Flicker, Leon, Ho , Ken K.Y., Golledge, Jonathan, Hankey, Graeme J., and Norman, Paul E. (2012) Associations of IGF1 and its binding proteins with abdominal aortic aneurysm and aortic diameter in older men. European Journal of Endocrinology, 166 (2). pp. 191-197.

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Abstract

Objective: Abdominal aortic aneurysm (AAA) is most prevalent in older men. Growth hormone secretion declines with ageing resulting in reduced insulin-like growth factor-I (IGF-I) levels. IGF-I and its binding proteins (IGFBPs) are expressed in vasculature, and lower IGF-I levels have been associated with cardiovascular risk factors and disease. However, the relationship of the IGF-I system to aortic dilation and AAA is unclear. We tested the hypothesis that circulating IGF-I and IGFBPs are associated with AAA and aortic diameter in older men.

Design: A cross-sectional analysis involving 3,981 community-dwelling men aged 70-89 years was performed.

Methods: Abdominal aortic diameter was measured with ultrasound. Plasma total IGF-I, IGFBP1 and IGFBP3 were measured by immunoassays.

Results: After adjustment for age, body mass index, waist:hip ratio, smoking, hypertension, dyslipidemia, diabetes, coronary heart disease and serum creatinine, higher IGF-I level was associated with AAA (odds ratio [OR]/1 SD increase=1.18, 95% confidence interval [CI]=1.05-1.33, p=0.006) as was the ratio of IGF-I/IGFBP3 (OR=1.22, 95%CI=1.10-1.35, p<0.001). IGF-I concentrations in highest compared to lowest quintile were significantly associated with AAA (Q5 vs Q1: OR=1.80, 95% CI 1.20-2.70, p=0.004) as were IGF-I/IGFBP3 ratios (Q5 vs Q1: OR=2.52, 95%CI=1.59-4.02, p<0.001). IGF-I and IGFBP1 were independently associated with aortic diameter (β=0.200, 95%CI=0.043-0.357, p=0.012 and β=0.274, 95%CI=0.098-0.449, p=0.002, respectively).

Conclusions: In older men, higher IGF-I and an increased ratio of IGF-I/IGFBP3 are associated with AAA, while IGFBP1 is independently associated with increased aortic diameter. Components of the IGF-I system may contribute to, or be a marker for, aortic dilation in ageing men.

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