Table 4 Target trial characteristics for ROBINS-I risk of bias
Exposure | Area (any size, type, population size) with income inequality |
|---|---|
Comparator | Comparable area size, type, population size with low-income inequality |
Outcome | Health outcomes (mortality, self-rated health) |
Confounding variables | Individual income Socioeconomic position |
Co-exposures | Tax system Strength of organized labour Universal healthcare |
Mediators | Psychosocial factors |
Factors that may undermine transportability/ explain statistical heterogeneity (based partly on [3, 13]). | • Gini vs non-Gini coefficient measure for income inequality • Time lag between exposure and outcome measurement • US vs non-US studies • Within country vs between country comparisons • Area type, size, and population size • Relative income inequality (e.g. Gini above vs below threshold) • Area level income • Education |