Neurocognitive clinical outcome assessments for inborn errors of metabolism and other rare conditions.

Well-defined and reliable clinical outcome assessments are essential for determining whether a drug provides clinically meaningful treatment benefit for patients. In 2015, FDA convened a workshop, "Assessing Neurocognitive Outcomes in Inborn Errors of Metabolism." Topics covered included special challenges of clinical studies of inborn errors of metabolism (IEMs) and other rare diseases; complexities of identifying treatment effects in the context of the dynamic processes of child development and disease progression; and the importance of natural history studies. Clinicians, parents/caregivers, and participants from industry, academia, and government discussed factors to consider when developing measures to assess treatment outcomes, as well as tools and methods that may contribute to standardizing measures. Many issues examined are relevant to the broader field of rare diseases in addition to specifics of IEMs.