IJE Advance Access originally published online on May 31, 2008
International Journal of Epidemiology 2008 37(4):805-815; doi:10.1093/ije/dyn093
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A hierarchical model for studying risk factors for childhood diarrhoea: a case–control study in a middle-income country
1 Instituto de Saúde Coletiva, Federal University of Bahia, Salvador, Brazil.
2 Escola Bahiana de Medicina e Saúde Pública, Salvador, Brazil.
3 Department of Pediatrics, School of Medicine, Federal University of Bahia, Salvador, Brazil.
4 London School of Hygiene and Tropical Medicine, London, UK.
5 Infectious Diseases Epidemiology Unit, London School of Hygiene and Tropical Medicine, London, UK.
* Corresponding author. Federal University of Bahia, Instituto de Saúde Coletiva, 40.110-170, Salvador, Bahia, Brazil. E-mail: mauricio{at}ufba.br
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Abstract |
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Objective To identify factors associated with diarrhoea occurrence in children in a city in a middle-income country, with high access to water and sanitation.
Methods A case–control study in the city of Salvador, north-eastern Brazil was conducted from November 2002 to August 2004. The study population consisted of children presenting at a health facility. A total of 1688 cases of diarrhoea and 1676 controls were selected. Data collection was by a questionnaire and structured observation during home visits. The explanatory variables were grouped according to a conceptual model defined previously. Analysis was done using a hierarchical approach, to provide a more dynamic view of the transmission characteristics of childhood diarrhoea. Non-conditional logistic regression was used, and odds ratio and population-attributable fractions were estimated.
Results Socioeconomic factors contributed most to determining diarrhoea occurrence, followed by interpersonal contact, while factors related to food preparation, the environment and water and sanitation made a smaller contribution.
Conclusion The findings indicate that the transmission of diarrhoea is influenced by factors from all hierarchical levels, with interpersonal transmission playing a relatively higher role than previously thought. This is compatible with a predominance of viruses and other agents spread by interpersonal routes including Shigella, Giardia and Cryptosporidium. Diarrhoea control strategies in similar settings (middle-income countries in which a large proportion of the population has access to water and sanitation) must give greater emphasis to policies geared towards reducing person-to-person transmission for the prevention of diarrhoea.
Keywords Diarrhoea, urban, transmission, person-to-person, risk factors, children, Brazil
Accepted 30 April 2008