Large observational datasets (such as Clinical Practice Research Datalink [CPRD]) provide opportunities to conduct clinical studies with efficient designs by utilising routinely collected resource-use data in randomised trials.

Full economic evaluations (i.e. estimation of the cost per quality-adjusted life-year [QALY]) can feasibly be conducted alongside such clinical studies by using a trial-based modelling approach to combine routinely collected data with supplementary data from the literature (such as utility values and unit costs).

This study design may be particularly suited to interventions that aim to optimise usual care and where the main clinical outcome is likely to result in a change in healthcare resource use within primary or secondary care.