Secular trends in serum lipid levels of a Middle Eastern adult population; 10 years follow up in Tehran lipid and glucose study

BACKGROUND: To examine trends in the population levels of serum lipids among a Middle-Eastern adult population with high prevalence of dyslipidemia. METHODS: A population-based cohort of adult Iranian participants, aged ≥20 years underwent four consecutive examinations between 1999-2001 and 2008-2011. Trends in age and multivariate-adjusted mean lipid levels were calculated using generalized estimating equations. RESULTS: At each of the 4 assessments, there were significant decreases in levels of total cholesterol (TC) (multivariate-adjusted means, 5.21 vs. 4.88 mmol/L in men; 5.42 vs. 5.07 mmol/L in women), triglycerides (TGs) (2.11 vs. 1.94 mmol/L in men; 1.88 vs. 1.74 mmol/L in women), and an increase in HDL-C level in both genders (0.95 vs. 1.058 mmol/L in men; 1.103 vs. 1.246 mmol/L in women) in multivariate analyses (all Ps <0.001); however, body mass index (BMI) significantly increased simultaneously (25.92 vs. 27.45 kg/m2 in men; 27.76 vs. 30.02 kg/m2 in women) (P < 0.001). There were significant (P < 0.001) increases in fasting plasma glucose (FPG) levels only among men (5.35 vs. 5.73 mmol/L). Results did not change after excluding participants that had cardiovascular disease or used lipid lowering drugs during follow-up. There were significant decreases in the prevalence of hypercholesterolemia, low HDL-C, hypertriglyceridemia (all Ps <0.001) during follow-up. Furthermore, the consumption of lipid lowering drugs significantly increased (P <0.001). CONCLUSION: During a 10 years follow-up, favorable trends were observed in the population levels of TC, triglycerides, HDL-C, which could not be fully accounted for by the increase observed in the consumption of lipid lowering drugs. These favorable trends were counterbalanced by the progressive increase in general obesity and FPG level.