Randomised controlled trials (RCTs) aim to estimate the causal effect of one or more interventions relative to a control. One type of outcome that can be of interest in an RCT is an ordinal outcome, which is useful to answer clinical questions regarding complex and evolving patient states. The target parameter of interest for an ordinal outcome depends on the research question and the assumptions the analyst is willing to make. This review aimed to provide an overview of how ordinal outcomes have been used and analysed in RCTs.

The largest randomised controlled trial (RCT) of neonatal caffeine therapy, the Caffeine for Apnea of Prematurity (CAP) trial, evaluated caffeine citrate at a loading dose of 20 mg/kg and a maintenance dose of 5–10 mg/kg/day.¹ Although caffeine is among the most commonly used neonatal medications, practice varies widely, and higher dosing has been reported.2 We hypothesised that caffeine practice may have evolved since the last survey conducted in the Australian and New Zealand Neonatal Network (ANZNN),³ despite limited data supporting higher caffeine doses.² We aimed to describe the current use of caffeine in very preterm infants as a fundamental step towards large RCTs of caffeine dosing.