Abstract 038: Association of 20-Year Changes in Cardiorespiratory Fitness with Incident Dyslipidemia Between Years 20 and 25 in the CARDIA Fitness Study

Abstract

Cardiorespiratory fitness levels are inversely associated with plasma levels of low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) and directly associated with high-density lipoprotein cholesterol (HDL-C) levels. However, few population-based studies have examined the association of fitness or changes in fitness on the risk of developing dyslipidemias. PURPOSE: To test the association of fitness at age 18-30 years with 25-year incidence of dyslipidemias, and to test the association of fitness changes over 20 years on the development of dyslipidemias in adults aged 43-55 years. METHODS: Fitness was determined based on the duration of a symptom-limited graded exercise treadmill test (modified Balke protocol) at baseline and Year 20 in Black and White men and women from the Coronary Artery Risk Development in young Adults (CARDIA) study. Lipid measurements were taken from fasting samples at baseline and years 5, 7, 10, 15, 20, and 25. Dyslipidemias were defined as: low HDL-C = <40 mg/dl, high TG = ≥200 mg/dl, and high LDL-C = ≥160 mg/dl (or self-reported use of lipid lowering medication). Cox proportional hazards regression models were used to test the association of baseline fitness with the incidence of dyslipidemias over 25 years (N ~4,000) in participants who did not have dyslipidemia at baseline. ANOVA modeling was used to test whether the mean 20-year changes in fitness differed between participants who developed incident dyslipidemia at Year 25 and those who did not (N= 2504). RESULTS: The 25-year incidence per 1000 person-years was 13.4 (N=1,096) for low HDL-C, 7.6 (N=711) for high TG, and 6.4 (N=569) for high LDL-C. Baseline fitness (SD 2.8 min) was inversely associated with 25-year incidence of low HDL-C (hazard ratio (HR): 0.94; 95% CI: 0.91 to 0.97 per SD in baseline fitness), high TG (HR: 0.90; 95% CI: 0.87 to 0.94 per SD), and high LDL-C (HR: 0.93; 95% CI: 0.89 to 0.97 per SD) in models that adjusted for age, sex, race, center, baseline BMI, and weight change and smoking status at time of event. After adjustment for age, sex, race, center, weight change, baseline treadmill time and BMI, participants who developed low HDL-C, high TG, and high LDL-C between Years 20 and 25 experienced larger 20-year declines in fitness than those who did not: (results shown as 20-year change in fitness in participants experiencing incident dyslipidemia at Year 25 vs participants who were normolipidemic at both time points) HDL-C: -3.1 vs -2.7 min, P=0.03; TG: -3.1 vs -2.8 min, P=0.004; LDL-C: -3.1 vs -2.8 min, P=0.04. CONCLUSIONS: Low fitness in young adults and larger decreases in fitness with aging are associated with the incidence of dyslipidemias.