Pneumonia in under-five year age children is the leading cause of morbidity and mortality in Ethiopia and other developing countries. Identifying modifiable risk factors for pneumonia could be important for proper management and prevention strategy of CAP.
The result of this study identified maternal age less than 25 years as a risk factor for CAP. There were similar studies conducted in different countries which reported young maternal age as risk factor for under-five children pneumonia. For example, a case-control study conducted in Brazilian metropolitan area and other research report of Southeast Asian countries reported young maternal age as the risk factors for developing under-five CAP (33, 34). However, a case-control study conducted in urban area of Oromia region and across sectional study conducted in Este town and the surrounding rural kebeles, Northwest Ethiopia reported absence of association between maternal age and occurrence of CAP in under-five children (30, 35).
The possible reason for this contrasting finding might be due to the different maternal age classification that the studies used based on their situations. The possible explanation for the current finding might be poor experience of younger mothers on child care and feeding. Additionally, there is higher risk of unintended and unwanted pregnancy in young mothers (36) which may lead to poor child care which might be a risk factor for occurrence of community acquired pneumonia in under-five children.
In this study large family size was also identified as risk factor of CAP. This finding is in line with similar study conducted in south-west Ethiopia which identified significant association between family size and community acquired pneumonia in under-five children (37). A cross sectional study conducted in the North West Ethiopia also showed significant association between family size and community acquired pneumonia in under-five children (35). But another study conducted in northwest Ethiopia reported no association between family size and CAP (38). This difference in finding could be due difference in study time which might have caused change in risk factors over time. The possible explanation could be that large family size usually connected with crowding at home which increase the transmission of respiratory tract infection through air droplet.
In this study, non-exclusive breast feeding showed significant association with occurrence of CAP. This finding is in line with a systematic review on the benefit of exclusive breast feeding that showed there were a 23 percent reduction in the occurrence of pneumonia among exclusively breastfed children (39). A Case-control study conducted in North Achefer District; Northwest Ethiopia also showed that exclusive breast feeding reduced the occurrence of community acquired pneumonia by 83 percent among under-five children (38). This difference in figures may be because the former is global study with average percent and the latter is done in a country with one the highest under five CAP burden. The possible explanation for this association could be the fact that breast feeding in early age protect infant’s (provide passive protection) against infection and has protective factor for reducing risk of respiratory illness including pneumonia.
Stunting was also identified as the risk factor for pneumonia in this study. The finding is consistent with study done in Bangladesh which showed the incidence of community acquired pneumonia is significantly higher among stunted children (40). A cross sectional study conducted in Este town and the surrounding rural kebeles, Northwest Ethiopia showed significant association between stunting and community acquired pneumonia, (35).
The possible explanation for this association could be that stunting indicates long term malnutritional of the children, which weakens child’s natural body defiance mechanism and the child becomes susceptible for the disease-causing agent. Children who had history of diarrhea in the last 15 days preceding the data collection were 2.4 times more likely to develop CAP. This finding is in line with the studies conducted in different parts of the world. For instance, a study conducted in Tigray region, Ethiopia, the occurrence of community acquired pneumonia was increased among children who have history of diarrhea (41). A Case-control study conducted in urban area of Oromia and Amhara regions, Ethiopia, also showed significant association between diarrhea and community acquired pneumonia in under-five children; children who had history of diarrhea in the past two weeks were 3 times more likely to develop community acquired pneumonia than children who have no history of diarrhea (30). Children who have concomitant illness like diarrhea which may compromise their nutritional status, have a lowered immunity and making them more susceptible to infectious agent including pneumonia.
From the variables related with indoor and environmental air pollution, use of charcoals as a source of cooking fuel shown statistically significant association with community acquired pneumonia in under-five children. This finding is consistent with study conducted in Este town, North-west Ethiopia which showed significant association between charcoal use and community acquired pneumonia in under-five children (35). This might be due to higher environmental/indoor air pollution from charcoal/wood use; air pollutants may adversely affect host defense mechanism of the air way against pathogens.
Lack of separate kitchen for and cooking in the main house were also other factors identified as a risk factor for community acquired pneumonia in under-five age children. This finding is consistent with a case-control study conducted in Ndola, Zambia, which showed significant association between not having separate room for cooking and occurrence of acute respiratory tract infection in under-five children (42). A cross sectional study conducted in Kenya also showed significant association between cooking near bed and acute respiratory tract infection in under-five children (43). Similar result is also reported at a cross sectional study conducted in Wondogenet district in Sidama zone, Ethiopia, which showed that absence of separate kitchen was 6.83 times higher risk for the acquirement of community acquired pneumonia in under-five age children (29). In these cases, risk of household air pollution is high, which contributes to pulmonary inflammation and tissue damage that favors the growth of ethologic agent and increase susceptibility of children to acquire pneumonia (3).
Finally, cigarette smoking was identified as risk factor for CAP; children who were living with the family member with cigarette smoking practice were 3.7 times more likely to develop pneumonia as compared to children from non-smoking parents. The result is supported by a prospective cohort and case-control study conducted in England and Gambia respectively showed significant association between household cigarette smoking and community acquired pneumonia in under-five children (44, 45).A case-control study conducted in southwest Ethiopia also showed significant association between household cigarette smoking and occurrence of community acquired pneumonia in under-five children, identified household cigarette smoking as independent risk factor for the occurrence of community acquired pneumonia in under-five children(37). But a case-control study conducted in Brazilian metropolitan area and a cross sectional study conducted in northwest Ethiopia reported that there were no association between parental cigarette smoking and the occurrence of community acquired pneumonia in under-five children (34, 35). This difference in the findings may be due to the study’s failure to indicate whether the smoking is indoor or outdoor. The possible explanation for the current finding could be that smoking contributes to the particulate load in indoor air and inhaling particles which limit the action of mucus and leading to cough in children. Further it causes lung tissue damage which leads to accumulation of fluid and favors the growth of disease-causing agent.