The Effect of China's Compulsory Education Reforms on Physiological Health in Adulthood: A Natural Experiment.

Lower education is related to higher biological risks for physiological health, but it remains unclear whether the risks can be reduced through policies aimed at increasing years of education. We utilized China's compulsory education reforms as a unique natural experiment, which stipulates that primary and lower secondary education is mandatory and free for all school-age children. Using a regression discontinuity design (RDD), we assessed the effect of the reform eligibility on biomarkers. The reforms resulted in an increase in years of education for those from communities with the middle 1/3 per capita income (PCI) (β = 2.44, 95% CI = 0.23 - 4.64). Reform eligibility had no impact on allostatic risks for the total sample (β = 0.065, 95% CI = -0.70 - 0.83) and for those from communities with the lowest (β = 0.35, 95% CI = -0.77 - 1.47) or highest third of PCI (β = 0.68, 95% CI = -0.64 - 2.00), while it reduced the metabolic risk (β = -0.14, 95% CI = -0.26 - -0.015) and total allostatic load (β = -1.58, 95% CI = -3.00 - -0.16) among those from communities with the middle third PCI. The results were confirmed by sensitivity analyses of different placebo cutoff points and bandwidths. The reforms led to better physiological health to some extent, but the effect only manifested in people from communities with a moderate community PCI, and had little impact on affluent or disadvantaged groups. Our findings stressed that the institutional context and respondents' socioeconomic environment must be taken into account when assessing the health impact of China's compulsory education reforms.