Associations of IGF1 and its binding proteins with abdominal aortic aneurysm and aortic diameter in older men

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