JMIR Publications

ABSTRACT

Background:

Cardiovascular diseases (CVD) are the leading cause of death globally. Demographic, behavioural, socioeconomic, healthcare and psychosocial variables, considered as risk factors for CVD, are routinely measured in population health surveys and therefore provide an opportunity to examine health transitions. Studying the drivers of health transitions in countries where multiple burdens of disease still linger (such as South Africa), compared with countries seen as models of ‘epidemiologic transition’, (such as England), can produce knowledge on where best to intervene and direct resources to reduce disease burden.

Objective:

The ExPoSE project (Explaining Population trends in cardiovascular risk: A comparative analysis of health transitions in South Africa and England) analyses micro-level data collected from multiple nationally-representative population health surveys conducted in these two countries between 1998 and 2017. Creating a harmonised dataset by pooling repeated cross-sectional surveys to model temporal trends in CVD risk is a daunting task due to changes in aspects such as survey content, question wording, inclusion of boost samples, weighting, measuring equipment and guidelines for data protection. Our objective was to create an harmonised dataset based on the annual Health Surveys for England, to estimate trends in overall CVD risk (primary outcome) and in its individual risk components (secondary outcome).

Methods:

We compiled a harmonised dataset to estimate temporal trends between 1998 and 2017 in the English adult population, including the primary and secondary outcomes, and potential drivers of those trends. Laboratory and non-laboratory based WHO and Globorisk CVD risk algorithms were used to estimate 10-year CVD risk. Sex-specific estimates of overall CVD risk and its components by survey year were calculated accounting for the complex survey design.

Results:

Overall, laboratory-based and non-laboratory-based 10-year CVD risk scores were calculated for n=33,628 and n=61,629 participants aged 40-74, respectively. The 10-year risk of CVD declined significantly over the last two decades in both sexes. In men, the mean (standard error: SE) of the laboratory-based WHO risk score was 10.1 (0.2) and 8.4 (0.2) in 1998 and 2017, respectively; corresponding figures in women were 5.6 (0.2) and 4.5 (0.2). In men, the mean (SE) of the non-laboratory-based WHO risk score was 9.6 (0.1) and 8.9 (0.2) in 1998 and 2017, respectively; corresponding figures in women were 5.8 (0.1) and 4.8 (0.1). CVD risk based on the Globorisk algorithms was lower in absolute terms, but the pattern of change was similar. Temporal trends in the individual risk components showed a complex pattern.

Conclusions:

Harmonised data from repeated cross-sectional health surveys can be used to identify and quantify the drivers of recent changes in cardiovascular disease risk at the population level.