Table 1.
Univariate and Bayesian multivariable infant mortality risk factor analysis, South Africa, 2007
| Indicator | Univariate analysis | Multivariable analysis | ||
|---|---|---|---|---|
| Zero-inflated Poisson model | Zero-inflated convolution CAR i spatial Poisson model | |||
| IRR (95% CI) | p-value | IRR (95% BCI ii) | p-value | |
| Proportion of previous siblings that have died | 1.135 (1.13,1.141) | <0.001 | 1.032 (0.989,1.081) | 0.088 |
| Proportion of mothers that have died | 1.108 (1.104,1.113) | <0.001 | 1.034 (1,1.073) | 0.025 |
| HIV antenatal sero-prevalence iii in 2007 | 1.035 (1.034,1.037) | <0.001 | 1.017 (1,1.037) | 0.022 |
| Ratio of male to female infants | 1.042 (1.041,1.043) | <0.001 | 1.021 (1.013,1.029) | <0.001 |
| Gini-coefficient for income inequality | 1.017 (1.016,1.019) | <0.001 | 1.003 (0.994,1.014) | 0.266 |
| Proportion of females with no schooling | 1.031 (1.03,1.032) | <0.001 | v | --- |
| Poor basic service delivery iv | 1.009 (1.009,1.009) | <0.001 | v | --- |
| Combined lack of female schooling and basic service delivery indicators | 1.012 (1.011,1.012) | <0.001 | 1.003 (0.993,1.002) | 0.912 |
| Constant (b0) | --- | --- | -1.198 (-1.664,-0.727) | --- |
| σ2ε (unstructured sub-district heterogeneity) | --- | --- | 0.446 (0.352,0.552) | --- |
| σ2φ (spatially structured heterogeneity) | --- | --- | 0.015 (0,0.142) | --- |
i: Incorporated an unstructured sub-district random effect and a structured normal CAR spatial random effect;ii: Bayesian credibility interval; iii: District level; iv: includes lack of basic service (water, toilet and rubbish disposal) and increasing ratio of infants to clinics within the sub-district
v: in multivariable model we have combined lack of female schooling with poor basic service delivery as they are strongly correlated (ρ = 0.5633, p < 0.01)