SUMMARY
As a case-control study, PERCH provides an opportunity to
assess risk factors for severe pneumonia in children in 7 developing
countries. Identifying risk factors and quantifying
the strength of their association with disease can guide strategies
to reduce the incidence of pneumonia in high-risk
populations, for example, by targeting vaccinations, reducing
exposure to indoor air pollution, and promoting schemes for
better healthcare utilization. We used existing public health
work and a broad literature review to capture all relevant risks,
and through a process of iterative review, first with an expert
body and later with the investigators at each of the 7 sites, we
included a core of essential questions in the PERCH casecontrol
study that were practical and would not result in
participant fatigue. Some risk factors are best defined by
physical measurements, which were beyond the resources of
the project; we will attempt to capture these exposures
through surrogate questions. Finally, although we strove to
standardize questions across all sites, the varying economic,
cultural, and geographic characteristics of the sites required
some flexibility in the ascertainment of the same risks in
different locations. Despite these challenges, the depth of the
evaluation of multiple risk factors across the breadth of the
PERCH sites should furnish valuable and new information
about the major risk factors for childhood pneumonia in
developing countries.