The inequality frame is usually flawed, and this is specially clear when the metholodogy and data to support the statements are biased. Let me suggest today this article that summarises perfectly common misunderstandings on this relationship. It would be a great input for a review and remake of recent papers.
The summary:
What is already known about this topic? A large body of research has examined the association between income inequality and average health. A separate body of research has explored income disparities in health. These two traditions should be seen as complementary, because high and rising income inequality is unlikely to affect the health of all socioeconomic groups equally.
What is added by this report? Although plausible theories suggest that rising income inequality can affect both average health and health disparities, empirical tests provide only modest support for some of these theories. We argue that understanding the effects of income inequality on health requires attention to mechanisms that affect the health of different income groups, thus changing average health, disparities in health, or both.
What are the implications for public health practice, policy, and research? Progress is likely to require disentangling direct effects of rising income inequality, which operate through changes in an individual’s own income, from indirect effects, which operate through changes in other people’s income. Indirect effects of rising income inequality may change a society’s political and economic institutions, social cohesion, culture, and norms of behavior, all of which can then affect individuals’ health even if their income remains unchanged.
PS. If someone needs an estimate of morbidity, please avoid inconsistent approaches. If someone needs policy guidance don't trust on cross-sectional data on such a difficult issue.
PS. My posts on health inequalities.
