Changes in lipid measures and incident coronary heart disease: Tehran Lipid & Glucose Study.

Background: Data on the impact of changes in lipid measures on subsequent coronary heart disease (CHD) outcomes are not consistent.

Methods: Study was conducted in 4459 adults, aged ≥30 years, free of cardiovascular disease at baseline who attended two consecutive examinations first in 1999-2001 and second in 2001-2003, and were followed up until March 31, 2010. Multivariate Cox proportional hazard regression adjusted for baseline lipid measures and other risk factors was calculated for a 1 standard deviation (SD) change in total cholesterol (TC), log-transformed triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) (calculated using modified Friedewald formula), non-HDL-C, TC/HDL-C and log-transformed TG/HDL-C. Effect of change in dyslipidemia (TC ≥6.21 mmol/L or TG ≥2.26 mmol/L or HDL-C <1.03 mmol/L or non-HDL-C ≥4.91 mmol/L) on incident CHD was examined, considering those with no dyslipidemia at baseline and follow-up as the reference group.

Results: During a mean follow-up of 9.5 years, 303 cases of CHD occurred. A 1-SD increase in TC, TG, non-HDL-C, TC/HDL-C and TG/HDL-C was associated with 14, 20, 19, 16 and 14% increase in risk of CHD event, respectively (all p values <0.05); the corresponding risk for LDL-C was [1.12 (0.99-1.27), P=0.07]. Participants with maintained dyslipidemia during follow-up had a significant risk for incident CHD [HR: 1.67(1.21-2.49)] compared to those with no dyslipidemia at baseline or follow-up.

Conclusions: Changes in TC, TG, and non-HDL-C, TC/HDL-C, TG/HDL-C were independent predictors of CHD events. Furthermore, maintained dyslipidemia was a strong predictor for CHD events.