Abstract: 247/250
Purpose: While much has been written about how distributed
networks address internal validity, external validity is rarely
discussed. We aimed to define key terms related to external validity,
discuss how they relate to distributed networks, and identify how three
networks (the US Food and Drug Administration’s Sentinel System, the
Canadian Network for Observational Drug Effect Studies [CNODES], and
PCORnet, the National Patient Centered Clinical Research Network,
initiated and supported by the Patient-Centered Outcomes Research
Institute.
Methods: We define external validity, target populations,
target validity, generalizability, and transportability and describe how
each relates to distributed networks. We then describe Sentinel, CNODES,
and PCORnet and how each approaches these concepts.
Results: Each network approaches external validity differently
Sentinel answers regulatory questions in the general US population using
data from commercial health plans and Medicare fee-for-service
beneficiaries and considers external validity when exploring outliers or
performing subgroup analyses to examine potential heterogeneity of
treatment effects. CNODES focuses on a Canadian target population but
includes UK and US data and thus has to make decisions about which
partners can be included in each analysis. PCORnet supports a wider
array of studies including randomized trials and often assesses whether
a given study will be representative of the wider US population.
Conclusions: There is no one-size-fits-all approach to external
validity within distributed networks. With these networks and
comparisons between their findings becoming a key part of
pharmacoepidemiology, there is a need to adapt tools for improving
external validity to the distributed network setting.