Age, period and cohort analysis of high cholesterol levels in Iranian adults over a 20-year period.

PURPOSE: Hypercholesterolemia is one of the most important modifiable risk factors of non-communicable diseases and data on their values in different societies and their trend of changes should be updated every couple of years. Many studies have focused on assessing the prevalence of high cholesterol. We must emphasise that most of these studies were cross-sectional and did not directly investigate the temporal trends of change for age, period and birth cohort (APC). The aim of this study is to evaluate the effect of age, period and birth cohort on the prevalence of borderline to high cholesterol levels in Iranian adult population.
METHODS: The data were collected from 110,302 subjects between 25 and 69 years of age over the period of 1990-2011. Data from these subjects were collected by using five national cross-sectional surveys conducted in 1990-91, 1999, 2003, 2007 and 2011. The APC effect on the prevalence of borderline and high cholesterol levels was assessed using the Intrinsic Estimator model.
RESULTS: The overall prevalence of borderline cholesterol level among male subjects was found to be lower than that of females (39.8% vs. 46.3%). Similarly, the prevalence of high cholesterol level in men was reported to be 13.1%, which was lower than the 18.0% calculated in women. The prevalence of borderline and high cholesterol levels increased with age in men between the ages of 45-49. Then it stayed quite steady and eventually declined. Then it stayed quite steady and eventually declined. The prevalence in women also increased with age, with its maximum rise after the ages of menopause and a slight decline at the ages of 65-69. As for the birth cohorts, the prevalence of borderline and high cholesterol levels followed a declining trend by going from earlier birth cohorts to the later ones.
CONCLUSION: The present study provides evidence that age, period and birth cohort affect the prevalence of borderline and high cholesterol levels. Thus, these factors should be considered when developing and implementing care plans for people with hypercholesterolemia. © Springer Nature Switzerland AG 2019.