Level and trend of total plasma cholesterol in national and subnational of Iran: a systematic review and age-spatio-temporal analysis from 1990 to 2016

Purpose: We aimed to estimate the level and trend of plasma cholesterol and raised total cholesterol (TC > 200 mg/dl) prevalence at national and subnational level of Iran. Methods: Nine national surveys and 27 studies, encompassing 3,505 unique points on over 500,000 adults, aged > 25 years with a report of laboratory measurement of TC were found. Age-spatio-temporal model and Gaussian Process Regression were used to estimate mean TC for each sex, 5-year age groups, and 31 provinces from 1990 to 2016. Results: At national level, age-standardized prevalence of TC > 200 mg/dL has decreased from 57·2%(53·3–61·1) to 22·4%(20·5–24·3) in women and 53·2%(49·1–57·3) to 18·0%(16·4–19·6) in men. TC distribution presented a condensation between 170-200 mg/dL. At subnational level, decreasing and converging patterns of raised TC prevalence were detected. Conclusion: The decrease in raised TC is likely the result of statin widespread use, food industry improvements, and the expanded primary health care.