Generation of List of Potential Risk Factors
First, we began with the risk factors prioritized by the Child
Health Epidemiology Reference Group (CHERG), an academic
review group constituted by the World Health Organization,
which examined .2000 studies on childhood pneumonia
published between 1961 and 2001 [12]. CHERG proposed
guidelines for the appropriate conduct of pneumonia etiology
studies and specified the minimum data that such studies
should collect to allow for valid comparisons and meta-analyses
of estimates across studies. These data included a description
of the study setting (eg, rural vs urban), geographical features
(eg, annual rainfall, altitude), sociodemographic factors (eg,
SES, crowding, indoor air pollution), concomitant health
problems (eg, malnutrition, HIV infection), and healthcare
factors (eg, immunization, access to healthcare). We took this
list, and whenever possible, adapted the specified factors for
ascertainment at an individual, not community, level to make
them compatible with a case-control study design.