Table 2.
Geospatial and non-spatial risk factors of endline infection status† among Ghanaian children in the combined Iron and No-iron groups (Brong-Ahafo Region 2010)
| Covariates | Estimate (95% CrI) on the exponential scale‡ | Range parameter in km (95% CrI) | SD of random effects (95% CrI) | ||
| Spatial | Compound | ||||
| Outcome 1: Inflammation and/or parasitaemia (n=1780) | |||||
| Intercept Age per month 6–23 months 24–35 months Sex (male reference) Length-for-age z-score Weight-for-length z-score Asset score Distance to health facility (km) Elevation (m) Baseline infection status Group Baseline iron status Baseline infection status*Group Baseline iron status*Group |
0.589 1.004 1.000 1.087 0.982 1.088 0.875 1.034 0.996 1.843 1.094 1.068 1.192 0.983 |
(0.337 to 1.072) (0.984 to 1.026) (0.962 to 1.038) (0.886 to 1.333) (0.896 to 1.075) (0.978 to 1.211) (0.779 to 0.980)* (0.933 to 1.136) (0.991 to 1.001) (1.359 to 2.500)* (0.826 to 1.448) (0.956 to 1.194) (0.775 to 1.833) (0.847 to 1.144) |
7.341 (2.928 to 15.84) | 0.525 (0.306 to 0.944) | 0.008 (0.004 to 0.029) |
| Outcome 2: Inflammation without parasitaemia (n=1780) | |||||
| Intercept Age per month 6-23 months 24-35 months Sex (male reference) Length-for-age z-score Weight-for-length z-score Asset score Distance to health facility (km) Elevation (m) Baseline infection status Group Baseline iron status Baseline infection status*Group Baseline iron status*Group |
0.183 1.009 0.956 1.139 1.092 1.054 0.871 1.012 0.999 1.055 1.009 1.001 1.523 1.033 |
(0.106 to 0.309)* (0.982 to 1.038) (0.904 to 1.009) (0.865 to 1.502) (0.968 to 1.230) (0.912 to 1.217) (0.750 to 1.010) (0.924 to 1.093) (0.994 to 1.003) (0.574 to 1.826) (0.713 to 1.427) (0.844 to 1.156) (0.718 to 3.300) (0.856 to 1.261) |
10.77 (8.767 to 25.54) | 0.407 (0.208 to 0.830) | 0.007 (0.004 to 0.028) |
| Outcome 3: Parasitaemia with fever (n=1939) | |||||
| Intercept Age per month 6-23 months 24-35 months Sex (male reference) Length-for-age z-score Weight-for-length z-score Asset score Distance to health facility (km) Elevation (m) Group Baseline infection status Baseline iron status Baseline infection status*Group Baseline iron status*Group |
0.003 1.008 0.978 0.939 0.992 0.966 1.029 1.057 0.997 0.891 0.730 1.028 1.209 0.954 |
(0.002 to 0.004)* (0.991 to 1.025) (0.948 to 1.008) (0.799 to 1.104) (0.923 to 1.064) (0.886 to 1.053) (0.937 to 1.130) (0.972 to 1.149) (0.993 to 1.002) (0.729 to 1.087) (0.452 to 1.114) (0.942 to 1.112) (0.639 to 2.282) (0.849 to 1.069) |
7.365 (3.225 to 15.18) | 0.464 (0.273 to 0.825) | 0.007 (0.004 to 0.028) |
| Outcome 4: All parasitaemia (n=1780) | |||||
| Intercept Age per month 6–23 months 24–35 months Sex (male reference) Length-for-age z-score Weight-for-length z-score Asset score Distance to health facility (km) Elevation (m) Baseline infection status Group Baseline iron status Baseline infection status*Group Baseline iron status*Group |
0.271 0.993 1.022 1.024 0.926 1.068 0.916 1.022 0.996 2.746 1.169 1.061 0.915 0.980 |
(0.135 to 0.571)* (0.966 to 1.021) (0.994 to 1.050) (0.814 to 1.287) (0.835 to 1.026) (0.947 to 1.204) (0.802 to 1.044) (0.902 to 1.164) (0.990 to 1.003) (1.910 to 3.951)* (0.862 to 1.587) (0.940 to 1.193) (0.555 to 1.508) (0.839 to 1.145) |
7.846 (3.384 to 16.06) | 0.712 (0.406 to 1.291) | 0.008 (0.004 to 0.029) |
*Statistical significance at the 0.05 level
†Infection status definitions:
Outcome 1: Inflammation and/or parasitaemia (binary): 1=CRP > 5 mg/L and/or any malaria parasitaemia, 0=CRP ≤ 5 mg/L and absence of parasitaemia;
Outcome 2: Inflammation without parasitaemia (binary): 1=CRP > 5 mg/L without malaria parasitaemia, 0=CRP ≤ 5 mg/L without parasitaemia;
Outcome 3: Parasitaemia with fever (count): any malaria parasitaemia with concurrent fever (axillary temperature >37.5°C) or history of reported fever (within 48 hours);
Outcome 4: All parasitaemia (binary): 1=any malaria parasitaemia (with/without fever), 0 = absence of parasitaemia
Model prior shape=1.117, model prior rate=0.157
‡Exponentials of posterior medians and 2.5% and 97.5% posterior quantiles of model parameters, with a value of 1.05 indicating that a variable increases the risk of infection by 5% (OR from logistic model for all binary outcomes; relative risk from Poisson model for count outcome)
Baseline infection status=baseline infection status (yes/no) according to corresponding definition
Baseline iron status=baseline serum ferritin concentration (µg/dL) corrected for CRP using the regression method (Namaste, Rohner, Suchdev, Kupka, Mei, Bhushan, Williams, Rowat, Raiten, Flores-Ayala, Clewes, 2016, unpublished) and re-scaled by multiplying by the inverse of the inter-quartile range
CrI, credible interval; CRP, C-reactive protein.