Historical state compulsory schooling laws and pandemic-era mortality: A quasi-experimental study

IntroductionLow educational attainment is associated with increased risk of COVID-19 mortality, but it remains unclear whether the link between education and COVID-19 mortality is causal or due to confounding factors, such as childhood socio-economic status or cognitive skills. To address this question, we evaluated whether older adults risk of COVID-19 mortality was associated with historical state-level compulsory schooling laws (CSLs) applicable when they were school-aged. We also evaluated whether that impact was unique to COVID-19 mortality or also applied to all-cause mortality, both before and during the pandemic. MethodsWe defined mortality outcomes using US death certificate data from Mar 2019-Dec 2021 for people born in the US before 1964 in three time periods: the year prior to the pandemic (Mar 2019-Feb 2020), pandemic year 1 (Mar 2020-Feb 2021), and pandemic year 2 (Mar-Dec 2021). We determined the population at risk using 2019 American Community Survey PUMS data with population weights, representing 78.7 million individuals born in the US before 1964. We linked individuals to the number of mandatory years of education defined by CSLs specific to their state of birth and years when school age. We estimated intention-to-treat effects of CSLs on mortality using logistic regressions controlling for state-of-birth fixed effects, birth year (linear and quadratic), sex, race, ethnicity, and state-level factors including percent urban, Black, and foreign-born (at age 6) and manufacturing jobs per capita and average manufacturing wages (at age 14). ResultsWe identified a dose-response relationship between CSLs and mortality. In the first year of the pandemic, people mandated to receive 8 vs 9 (reference) years of education had higher odds of COVID-19 mortality (Odds Ratio [OR]: 1.15; 95% Confidence Interval [CI]: 1.10, 1.19), while those mandated to receive 10 vs 9 (reference) years of education had lower odds of COVID-19 mortality (OR: 0.96; 95% CI: 0.94, 0.98). The association of CSLs with COVID-19 mortality was similar in pandemic years 1 and 2; for all-cause mortality in pandemic years 1 and 2; and for all-cause mortality in the year prior to the pandemic. Results were robust to alternative model specifications. ConclusionsThese findings support a causal benefit of education for reduced mortality during the COVID-19 pandemic. State investments in childrens education may have reduced pandemic-era mortality decades later. Our research has implications beyond the pandemic context, as our results suggest the observed relationship mirrors a pre-existing relationship between CSLs and all-cause mortality.