Modelling the direct and indirect associations between anthropometric and behavioural factors when predicting atherogenic risk index (TC/HDL-C) ratio

To identify the association between body size and atherogenic risk index (Total Cholesterol/High Density Lipoprotein (TC/HDL) ratio) associated with ischemic heart disease (IHD). Allometric models were used to reveal the association between body size and social behaviours associated with TC:HDL based on the effect sizes obtained from the log-transformed allometric models. Mediation analysis was used to explain why moderate (MPA) or vigorous physical activity (VPA) were strongly associated with body size dimensions or directly associated with TC/HDL. An allometric model for the atherogenic risk index (TC/HDL) ratio identified waist circumference (WC) and smoking as having the strongest association (strongest effect sizes) with cholesterol-related indices and hence IHD. A strong negative exponent or effect associated with height was also identified, suggesting that taller individuals will inherently have lower cholesterol-related indices. The mediation analysis identified that MPA and VPA were both strongly associated with reducing WC but only VPA was directly associated with the TC/HDL. These results confirm that taller, non-smokers who have smaller WC are more likely to have a lower atherogenic risk index (TC/HDL) ratio and hence be at reduced risk of IHD. Participation in regular moderate activity to reduce their WC is not necessarily or directly associated with lower atherogenic risk index (TC/HDL) and hence a lower risk of IHD. Being taller with smaller WC, possibly but not necessarily due to taking MVPA, was associated with a lower atherogenic risk index (TC/HDL-C) ratio and hence have lower risk of IHD.