IGFBP3 and cardiovascular disorder: The fact that after removing persons with cardiovascular disease in the sensitivity analysis, only the 60–64y IGF-I/IGFBP-3 molar ratio and ΔIGF-I/IGFBP-3 ratio retained significant association with QTc, adds credence to the notion that it is the free, bioavailable IGF-I which most strongly determines the electrophysiological effect observed.