Neo-materialist theory and the temporal relationship between income inequality and longevity change

This study uses a neo-materialist perspective to develop theoretical predictions regarding temporal ties between income inequality and change in population health. The argument focuses on the relationship between income inequality and adoption of longevity-enhancing innovations. It asserts that longevity change should be influenced by preexisting levels of income inequality and that, consequently, income inequality can cause differential longevity improvement across jurisdictions even if inequality levels remain unchanged. State-level U.S. data from 1970 to 2000 are used to jointly model the effects of initial levels and change in income inequality on 10-year life expectancy change. Results confirm that states with higher levels of inequality experienced less subsequent improvement in life expectancy. Contrary to findings from prior research, analyses also reveal a strong negative association between change in inequality and change in longevity once initial levels of inequality and other state characteristics are controlled. Finally, direct tests of the relationship between income inequality and the adoption of innovations in quality of medical care indicate that the two are highly related and that differences in the average quality of care can account for the negative cross-sectional association between income inequality and life expectancy.本研究采用新唯物主义（neo-materialist）视角，针对收入不平等与人群健康变化之间的时序关联构建理论预测。本研究的核心论证聚焦于收入不平等与长寿增益型创新的采纳行为之间的关联。研究主张，人群寿命的变化应受既有收入不平等水平的影响；据此，即便收入不平等水平维持不变，收入不平等仍可导致不同行政辖区间的寿命改善程度产生分化。本研究采用1970至2000年的美国州级数据，联合建模初始收入不平等水平及其变化对10年期预期寿命变化的影响效应。研究结果证实，初始不平等水平更高的州，其后续的预期寿命改善幅度显著更低。与既往研究结论相悖的是，在控制了初始不平等水平及其他州级特征变量后，分析结果还显示：不平等程度的变化与寿命变化之间存在显著的负相关关系。最后，针对收入不平等与医疗服务质量创新采纳之间关联的直接检验表明，二者存在高度相关性，且医疗服务平均质量的差异能够解释收入不平等与预期寿命之间的负向截面关联。