Is survival and neurodevelopmental impairment at 2 years of age the gold standard outcome for neonatal studies?

To cite: Marlow N. Arch Dis Child Fetal Neonatal Ed 2015;100:F82–F84. INTRODUCTION Designing perinatal trials is a continuing challenge. In the process, the choice of primary outcome is one of the critical decisions and one that will determine the necessary trial size and ultimately the success or failure. The primary outcome should be directly causally relevant to the intervention under study and the difference sought must be clinically relevant. Alongside the test of efficacy, there is also a need to ensure that a treatment is safe. Few trials are now designed without a measure of developmental outcome at 18–24 months as a primary or coprimary outcome. This is a complex outcome, being a composite usually of death and four to five domains of developmental impairment, based on value judgments as to severity of impairment in the areas of motor, cognitive, hearing and visual functions, and sometimes communication. I would like to address a range of issues with the use of this as a composite outcome and the extent to which we should rely on it to show benefit when we are assessing research based evidence about interventions. This paper discusses the relevance of 2-year outcomes in several trials and develops some ideas as to how we might consider 2-year outcomes, in terms of their interpretation and in the implementation of trial data into practice.