Cooking and Season as Risk Factors for Acute Lower Respiratory Infections in African Children: A Cross-Sectional Multi-Country Analysis

Background Acute lower respiratory infections (ALRI) are a leading cause of death among African children under five. A significant proportion of these are attributable to household air pollution from solid fuel use. Methods We assessed the relationship between cooking practices and ALRI in pooled datasets of Demographic and Health Surveys conducted between 2000 and 2011 in countries of sub-Saharan Africa. The impacts of main cooking fuel, cooking location and stove ventilation were examined in 18 (n = 56, 437),9 (n = 23, 139) and 6 countries (n = 14, 561) respectively. We used a causal diagram and multivariable logistic mixed models to assess the influence of covariates at individual, regional and national levels. Results Main cooking fuel had a statistically significant impact on ALRI risk (p<0.0001),with season acting as an effect modifier (p = 0.034). During the rainy season, relative to clean fuels, the odds of suffering from ALRI were raised for kerosene (OR 1.64;CI: 0.99, 2.71),coal and charcoal (OR 1.54;CI: 1.21, 1.97),wood (OR 1.20;CI: 0.95, 1.51) and lower-grade biomass fuels (OR 1.49;CI: 0.93, 2.35). In contrast, during the dry season the corresponding odds were reduced for kerosene (OR 1.23;CI: 0.77, 1.95),coal and charcoal (OR 1.35;CI: 1.06, 1.72) and lower-grade biomass fuels (OR 1.07;CI: 0.69, 1.66) but increased for wood (OR 1.32;CI: 1.04, 1.66). Cooking location also emerged as a season-dependent statistically significant (p = 0.0070) determinant of ALRI, in particular cooking indoors without a separate kitchen during the rainy season (OR 1.80;CI: 1.30, 2.50). Due to infrequent use in Africa we could, however, not demonstrate an effect of stove ventilation. Conclusions We found differential and season-dependent risks for different types of solid fuels and kerosene as well as cooking location on child ALRI. Future household air pollution studies should consider potential effect modification of cooking fuel by season

Cooking and Season as Risk Factors for Acute Lower Respiratory Infections in African Children: A Cross-Sectional Multi-Country Analysis

Background Acute lower respiratory infections (ALRI) are a leading cause of death among African children under five. A significant proportion of these are attributable to household air pollution from solid fuel use. Methods We assessed the relationship between cooking practices and ALRI in pooled datasets of Demographic and Health Surveys conducted between 2000 and 2011 in countries of sub-Saharan Africa. The impacts of main cooking fuel, cooking location and stove ventilation were examined in 18 (n = 56, 437),9 (n = 23, 139) and 6 countries (n = 14, 561) respectively. We used a causal diagram and multivariable logistic mixed models to assess the influence of covariates at individual, regional and national levels. Results Main cooking fuel had a statistically significant impact on ALRI risk (p<0.0001),with season acting as an effect modifier (p = 0.034). During the rainy season, relative to clean fuels, the odds of suffering from ALRI were raised for kerosene (OR 1.64;CI: 0.99, 2.71),coal and charcoal (OR 1.54;CI: 1.21, 1.97),wood (OR 1.20;CI: 0.95, 1.51) and lower-grade biomass fuels (OR 1.49;CI: 0.93, 2.35). In contrast, during the dry season the corresponding odds were reduced for kerosene (OR 1.23;CI: 0.77, 1.95),coal and charcoal (OR 1.35;CI: 1.06, 1.72) and lower-grade biomass fuels (OR 1.07;CI: 0.69, 1.66) but increased for wood (OR 1.32;CI: 1.04, 1.66). Cooking location also emerged as a season-dependent statistically significant (p = 0.0070) determinant of ALRI, in particular cooking indoors without a separate kitchen during the rainy season (OR 1.80;CI: 1.30, 2.50). Due to infrequent use in Africa we could, however, not demonstrate an effect of stove ventilation. Conclusions We found differential and season-dependent risks for different types of solid fuels and kerosene as well as cooking location on child ALRI. Future household air pollution studies should consider potential effect modification of cooking fuel by season

Number of observations, cooking fuel and rainy season in final dataset, by country.

<p>Please note that the South African DHS data from 2003 are not in the public domain and could therefore not be included in this analysis.</p><p>^a Dataset without missing values in any explanatory variable of the final model (maternal smoking, time to nearest water source, shelter, and vaccination index, paternal and maternal education, child sex and age, birth order, stunting, geographic location).</p><p>Number of observations, cooking fuel and rainy season in final dataset, by country.</p

Results of the logistic mixed model regressions of ALRI for stove ventilation and cooking location.

<p>* refers to an interaction between two variables. Please note, the presented ORs are coming from the estimate of the corresponding beta and are of pure statistical interest. Interpretable ORs for variables with interaction terms can be found in the text.</p><p>pLR is the p-value of the LR-Test comparing the final model with the final model without the corresponding covariate.</p><p>nc. Not calculable due to very low number of households cooking with kerosene (n = 10 housholds were coded as “Clean fuel”).</p><p>^a Dataset without missing values in any explanatory variable of the final model (maternal smoking, time to nearest water source, shelter, and vaccination index, paternal and maternal education, child sex and age, birth order, stunting, geographic location) for the following countries: Ghana, Madagascar, Malawi, Namibia, Uganda, and Zambia</p><p>^b Dataset without missing values in any explanatory variable of the final model (maternal smoking, time to nearest water source, shelter, and vaccination index, paternal and maternal education, child sex and age, birth order, stunting, geographic location) for the following countries: Ethiopia, Ghana, Kenya, Madagascar, Malawi, Namibia, Uganda, Zambia, and Zimbabwe</p><p>^c Both p-values relate to LR-Tests comparing (i) the final model with a model without main or interaction effects, and (ii) the final model with a model with main effects but without interaction effects.</p><p>Results of the logistic mixed model regressions of ALRI for stove ventilation and cooking location.</p

Flow diagram of pooled DHS dataset illustrating where countries and observations are lost due to missing variables or values in analysis of (a) main cooking fuel, (b) cooking location and (c) stove ventilation.

<p>^a Benin, Burkina Faso, Cameroon, Ethiopia, Gabon, Ghana, Guinea, Kenya, Madagascar, Mali, Malawi, Mozambique, Namibia, Niger, Rwanda, Senegal, Tanzania, Uganda, Zambia, and Zimbabwe. ^b Ethiopia, Ghana, Kenya, Madagascar, Malawi, Namibia, Uganda, Zambia, and Zimbabwe. ^c Ghana, Madagascar, Malawi, Namibia, Uganda, and Zambia. ^d Missing values in explanatory variables: Maternal smoking, crowding, time to nearest water source, shelter index, wealth index, vaccination index, paternal education, maternal education, possession of health card, child sex, child age, birth order, breastfeeding duration, stunting, geographic location, sex of household head, age of household head. ^e Variables not selected in final model: Crowding, wealth index, possession of health card, breastfeeding duration, sex of household head, age of household head. ^f Three countries could be added because crowding was not selected in the final model and it was the only missing variable in Burkina Faso, Guinea, and Senegal. ^g Missing values in explanatory variables: Maternal smoking, time to nearest water source, shelter index, paternal education, maternal education, child sex, child age, birth order, stunting, vaccination index, geographic location.</p