The foundational basis for the pneumonia etiology results from the PERCH (Pneumonia Etiology Research for Child Health) project have been published in a 23-paper supplement in Clinical Infectious Diseases. The publication details the context, methods, and preparatory results that will inform the final pneumonia etiology estimates, expected to be available in late 2017.
PERCH is the largest pneumonia etiology study conducted since the formative pneumonia etiology studies of the 1980s, encompassing nine sites in seven countries and with a total enrollment of over 4,000 pneumonia cases and 5,000 controls.
Thanks to the collaborating efforts of individuals from a breadth of institutions, the study methodology is rigorous, standardized, and analytically novel. The etiology estimates that will be available at a later date are critical for decision makers involved in the fight against pneumonia; quantitative information about etiology allows researchers, policymakers, funders, and pharmaceutical manufacturers to strategically target the bacterial and viral causes of pneumonia that are most significant.
The current supplement describes important technical lessons pertaining to respiratory pathogen detection. For example, results suggest that blood samples from healthy subjects are not as sterile as previously assumed, as the data revealed a similar proportion of whole blood pneumococcal PCR-positive results in healthy children as in those with clinically diagnosed pneumonia.
Another article in the supplement describes an integrated analysis that will be used to determine pneumonia etiology, performed using an analytic method developed by the PERCH investigators (Bayesian Analysis Kit for Etiology Research, or BAKER). It is the first to enable the integration of results from multiple diagnostic methods and specimens to reliably estimate etiology, accounting for imperfect sensitivity and specificity of laboratory testing methods.
In addition to the forthcoming final etiology results, the study produced a robust dataset and specimen bank, and a cache of valuable resources including study procedures and protocols, clinical standardization training materials, and data collection forms; these materials are “open source” and available via the PERCH website as resources for use by investigators who might benefit from these for other research projects. The complete supplement text can be viewed and downloaded here.