Background: Tracking analysis of serum cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and the TC/HDL-C ratio was carried out by a new method based on generalized estimating equations (GEE).
Methods: Longitudinal data were derived from the Amsterdam Growth and Health Study, in which 181 subjects were measured six times from age of 13 years to the age of 27 years.
Results: Tracking coefficients (interpretable as coefficients of stability over time) calculated over a 15-year period with GEE for TC were 0.71 [95% confidence interval (CI) 0.60-0.74]; for HDL-C, males, 0.51 (95% CI 0.34-0.69); for HDL-C, females, 0.65 (95% CI 0.53-0.77); and for the TC/HDL-C ratio 0.71 (95% CI 0.63-0.79). The changes in TC were positively influenced by both body fatness (standardized regression coefficient beta = 0.13; 95% CI 0.04-0.21) and daily physical activity (beta = 0.08; 95% CI 0.00-0.16), and the changes in the TC/HDL-C ratio were positively influenced by body fatness (beta = 0.11; 95% 0.03-0.19).
Conclusions: GEE tracking coefficients for TC and for the TC/HDL-C ratio were higher than the coefficients for HDL-C. Furthermore, multivariate analyses showed a positive influence of body fatness and daily physical activity measured at 13 years of age on the changes in TC over time. No relations were found between any of the biological, psychological, or lifestyle parameters and the changes in HDL-C, while the changes in the TC/HDL-C ratio were positively related to body fatness measured at 13 years of age.