Total cholesterol/HDL-C ratio versus non-HDL-C as predictors for ischemic heart disease: a 17-year follow-up study of women in southern Sweden

Background: A distorted blood lipid profile is an important risk factor for ischemic heart disease (IHD) but the predictive ability of the different lipid measures has rarely been studied. Our aim was to examine and compare, in a large sample of women, the predictive ability of total cholesterol/HDL cholesterol ratio (TC/HDL-C) and non-HDL-C in relation to IHD, adjusted for age, exercise, smoking, waist-hip ratio, blood pressure, and diabetes mellitus. Methods: Between 1995 and 2000, a total of 6537 women aged 50–59 years from the Women’s Health in Lund area (WHILA) study in southern Sweden were included and underwent a baseline examination. The women were followed through national registers for incidence of IHD during a mean follow-up of 17 years. The prediction accuracy was estimated through Harrell’s C and Akaike Information Criterion (AIC). Results: Increasing TC/HDL-C as well as non-HDL-C showed strong associations with IHD, with the highest risk in the 5th quintile, where the HR was 2.30 (95% CI: 1.70–3.11) for TC/HDL-C and 1.67 (95% CI: 1.25–2.24) for non-HDL-C, after adjustments. Comparisons using Harrell’s C and AIC indicated that TC/HDL-C has a slightly higher predictive ability than that of non-HDL-C (Harrell’s C 0.62 and 0.59 respectively, p = 0.003 for difference, age-adjusted model; AIC for TC/HDL-C < AIC for non-HDL-C). Conclusions: TC/HDL-C ratio and non-HDL-C are both clinical predictors for IHD in middle-aged women. The results indicate that the predictive ability of TC/HDL-C was higher than that of non-HDL-C; however, non-HDL-C was linearly related to IHD (p = 0.58) and may be easier to calculate and interpret in clinical practice, for early identification of future IHD in women.