Does the union make us strong? Labor unions, health, and health inequities in the United States

Recently, life expectancy in the U.S. has stagnated or declined for the poor and working classes and risen for the middle and upper classes. Declining labor union density – the percent of workers belonging to labor unions – has contributed to burgeoning income inequity. In this dissertation, we examined the relationship between unionism and health, and tested whether declining union density has exacerbated racial and educational mortality inequities. In the first study, we analyzed the state-level relationships between union density, mortality, and mortality inequities from 1986-2016. State-level all-cause mortality and overdose/suicide mortality overall and by gender, gender-race, and gender-education came from CDC, while state-level union density came from the Current Population Survey. Using inverse-probability-of-treatment-weighted Poisson models with state and year fixed effects, we estimated three-year-moving-average union-density’s effects on the following year’s mortality rates. Then, we tested for gender, gender-race, and gender-education effect-modification. Finally, we estimated how racial and educational all-cause mortality inequities would change if union density increased to baseline levels. Overall, a 10% increase in union density was associated with a 17% relative decrease in overdose/suicide mortality (95% CI: 0.70, 0.98), or 5.7 lives saved per 100,000 person-years (95% CI: -10.7, -0.7). Union density’s absolute (lives-saved) effects on overdose/suicide mortality were stronger for men than women, but its relative effects were similar across genders. However, our estimates were sensitive to the analytic approach. Moreover, union density had little effect on all-cause mortality overall or across subgroups, and modeling suggested union-density increases would not affect mortality inequities. In the second study, we analyzed the individual-level relationship between union membership, self-rated health (SRH), and moderate mental illness. The union membership and SRH analyses used data on 16,719 Panel Study of Income Dynamics (PSID) respondents followed between 1985 and 2017, while the union membership and mental-illness analyses included 5,813 PSID respondents followed between 2001 and 2017. Using the parametric g-formula, we contrasted cumulative incidence of the outcomes under two hypothetical scenarios, one in which we set all employed-person-years to union-member employed-person-years (union scenario), and one in which we set no employed-person-years to union-member employed-person-years (non-union scenario). We also examined whether the scenarios’ effects varied by gender, gender-race, and gender-education in stratified models. Overall, the union scenario did not reduce incidence of poor/fair SRH (RR: 1.01, 95% CI: 0.95, 1.09; RD: 0.01, 95% CI: -0.03, 0.04) or moderate mental illness (RR: 1.02, 95% CI: 0.92, 1.12; RD: 0.01, 95% CI: -0.04, 0.06) relative to the non-union scenario. These effects largely did not vary by subgroup. In the final study, we examined the individual-level relationship between union membership, mortality, and mortality inequities using data on 23,022 PSID respondents followed between 1979 and 2017. First, using the parametric g-formula, we contrasted cumulative incidence of mortality in the union and non-union scenarios. Next, we examined whether the scenarios’ effects varied by race or education in stratified models. Finally, we estimated how racial and educational mortality inequities would change if union density had remained at 1979 levels throughout follow-up rather than that at 2015 levels. Overall, the union scenario modestly reduced mortality (RR: 0.90, 95% CI: 0.80, 0.99; RD per 1,000: -18.7, 95% CI: -36.5, -0.9) relative to the non-union scenario. However, the scenarios’ effects largely did not vary by subgroup, and modeling did not suggest racial and educational mortality inequities would lessen if union density had remained at baseline levels. Overall, we found little evidence that declining union density (at least as operationalized in this dissertation) explained changing racial and educational mortality inequities in the U.S. over the last several decades. However, our results did suggest that increasing state-level union density might decrease overdose/suicide mortality, and that increasing individual-level union membership might decrease all-cause mortality