Educational inequalities in mortality and their mediators among generations across four decades: nationwide, population based, prospective cohort study based on the ChinaHEART project

Abstract

Abstract Objectives To assess the different educational inequalities in mortality among generations born between 1940 and 1979 in China, and to investigate the role of socioeconomic, behavioural, and metabolic factors as potential contributors to the reduction of educational inequalities. Design Nationwide, population based, prospective cohort study. Setting The ChinaHEART (China Health Evaluation And risk Reduction through nationwide Teamwork) project in all 31 provinces in the mainland of China. Participants 1 283 774 residents aged 35-75 years, divided into four separate cohorts born in 1940s, 1950s, 1960s, and 1970s. Main outcome measures Relative index of inequality and all cause mortality. Results During a median follow-up of 3.5 years (interquartile range 2.1-4.7), 22 552 deaths were recorded. Among the four generations, lower education levels were found to be associated with a higher risk of all cause death: Compared with participants with college level education or above, the hazard ratio for people with primary school education and below was 1.4 (95% confidence interval 1.2 to 1.7) in the 1940s cohort, 1.8 (1.5 to 2.1) in the 1950s cohort, 2.0 (1.7 to 2.4) in the 1960s cohort, and 1.8 (1.4 to 2.4) in the 1970s cohort. Educational relative index of inequality in mortality increased from 2.1 (95% confidence interval 1.9 to 2.3) in the 1940s cohort to 2.6 (2.1 to 3.3) in the 1970s cohort. Overall, the mediation proportions were 37.5% (95% confidence interval 32.6% to 42.8%) for socioeconomic factors, 13.9% (12.0% to 16.0%) for behavioural factors, and 4.7% (3.7% to 5.8%) for metabolic factors. Except for socioeconomic measurements, the mediating effects by behavioural and metabolic factors decreased in younger generations. Conclusion Educational inequalities in mortality increased over generations in China. Improving healthy lifestyles and metabolic risk control for less educated people, especially for younger generations, is essential to reduce health inequalities.