Measuring and characterising worldwide trends in blood lipids

Abstract

Non-optimal cholesterol levels are a major modifiable risk factor for cardiovascular diseases (CVDs), the world’s leading causes of death. My thesis aimed to provide consistent and comparable estimates on national, regional and global trends in blood lipids. Data were collated, via the NCD Risk Factor Collaboration (NCD-RisC) network, from population-based studies that measured blood lipids. A total of 1,127 population-based studies from 1980 to 2018, with measurement of blood lipids on 102.6 million individuals aged 18 years and older, were pooled for this analysis. I used a Bayesian hierarchical model to estimate trends in mean total, high-density lipoprotein (HDL) and non-HDL cholesterol levels for 200 countries and territories. High non-HDL cholesterol, and CVD deaths associated with it, has transitioned from being a distinct feature of high-income countries in northwestern Europe, north America and Australasia in 1980 to one that affects middle-income countries, especially those in east and southeast Asia in 2018. This transition has occurred as a consequence of opposing trends, with non-HDL cholesterol declining in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe, while rising in low- and middle-income countries, particularly in east and southeast Asia. Globally, high non-HDL cholesterol was responsible for an estimated 3.9 million deaths in 2017, half of which occurred in east, southeast and south Asia. Clinical and public health strategies to lower non-HDL cholesterol, including population-wide policies and individual-level interventions to improve diet and enhance treatment coverage, are now needed in virtually all countries to tackle CVD burden.