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Table 1 Univariate and Bayesian multivariable infant mortality risk factor analysis, South Africa, 2007

From: Infant mortality in South Africa - distribution, associations and policy implications, 2007: an ecological spatial analysis

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) ---
  1. 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
  2. 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)