Table 3

Meta-regression models explaining study heterogeneity on the association between income inequality and mortality

Variables (number of studies)	Bivariate				Multivariate
	Bivariate				Model 1			Model 2			Model 3			Model 4
	β	SE	p	τ²^*	β	SE	p	β	SE	p	β	SE	p	β	SE	p
Intercept	–	–	–		0.027	0.023	0.23	0.047	0.024	0.05	0.045	0.034	0.19	0.045	0.024	0.06
Average population (1000)
Small: 8–14 (4)	Referent
Large: 470–4880 (5)	−0.033	0.025	0.19	2.8⁻³	−0.040	0.021	0.06	−0.010	0.026	0.69	−0.015	0.028	0.59	−0.010	0.026	0.70
Continuous (per 500 000 population)	−0.004	0.003	0.29	3.0⁻³
Median GINI
<Median (=0.30) (4)	Referent				Referent
≥Median (5)	0.073	0.027	0.006	2.1⁻³	0.077	0.025	0.002
Baseline data
≤1990 (6)	Referent							Referent
>1990 (3)	0.057	0.022	0.01	2.2⁻³				0.052	0.026	0.04
Follow-up duration
≤7 years (4)	Referent										Referent
>7 years (5)	0.054	0.029	0.06	2.6⁻³							0.046	0.033	0.17
Adjusting for area income
No (5)	Referent													Referent
Yes (4)	0.059	0.022	0.009	2.2⁻³										0.054	0.025	0.03
τ²^*	–	–	–	–	1.8⁻³			2.3⁻³			2.7⁻³			2.3⁻³

Intercepts in these meta-regression models represent the degree of the associations between income inequality and mortality when explanatory variables are in a referent category or zero (for continuous explanatory variables).
↵* τ² represents the magnitude of residual heterogeneity.