Educational inequalities in mortality and their mediators among generations across four decades: nationwide, population based, prospective cohort study based on the ChinaHEART project (2024)

1. Jiapeng Lu, associate professor1,
2. Chaoqun Wu, assistant professor1,
3. Xiaoyan Zhang, statistician1,
4. Yang Yang, assistant professor1,
5. Jianlan Cui, senior research fellow1,
6. Wei Xu, senior research fellow1,
7. Lijuan Song, senior research fellow1,
8. Hao Yang, research fellow1,
9. Wenyan He, research fellow1,
10. Yan Zhang, research fellow1,
11. Jing Li, professor1,
12. Xi Li, associate professor1 2 3

1. ¹National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
2. ²Shenzhen Clinical Research Center for Cardiovascular Diseases, Fuwai Hospital Chinese Academy of Medical Sciences, Shenzhen, Shenzhen, China
3. ³Central China Subcenter of the National Center for Cardiovascular Diseases, Zhengzhou, China

1. Correspondence to: Xi Li xi.li{at}nccd.org.cn

• Accepted 1 June 2023

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.

Footnotes

• Contributors: JLu and CW contributed equally to the paper as joint first authors. XL (xi.li{at}nccd.org.cn) and JLi (lijing{at}fuwai.com) are joint corresponding authors. XL and JLi conceived the ChinaHEART project and take responsibility for its all aspects. JLu and CW conceived this article. JLu and CW wrote the manuscript, with further contributions from XZ, YY, JC, WX, LS, HY, WH, YZ, JLi, and XL. CW, XZ, and JLu completed all the statistical analysis. All authors interpreted data, contributed to critical revisions, and read and approved the final version of the article. The corresponding author (XL) attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

• Funding: This study was supported by the CAMS Innovation Fund for Medical Science (2021-1-I2M-011); the National High Level Hospital Clinical Research Funding (2022-GSP-GG-4, 2023-GSP-RC-20); the Ministry of Finance of China and National Health Commission of China; the 111 Project from the Ministry of Education of China (B16005). The funder of the study had no role in study design, data collection, data analysis, data interpretation, or the decision to submit the manuscript for publication.

• Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/disclosure-of-interest/ and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

• The lead author (the manuscript’s guarantor) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

• Dissemination to participants and related patient and public communities: Results of this study will be disseminated to study participants and the general public via emailed newsletters relevant to the individual cohorts, institutional and cohort specific websites, and social media channels, where available.

• Provenance and peer review: Not commissioned; externally peer reviewed.

Data availability statement

The data are not publicly available. The China Health Evaluation And risk Reduction through nationwide Teamwork (ChinaHEART) project only provides conditional data access for qualified researchers with legitimate requests; a formal application and research proposal is required. Please contact cvd-project{at}nccd.org.cn to seek approval for data access.

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