Missing data in trial-based cost-effectiveness analysis: the current state of play.

Randomised controlled trial (RCT)-based cost-effectiveness analyses, which are prone to missing data, are increasingly used in healthcare technology assessment. This has highlighted the need for appropriate methodological approaches to the handling of missing data. This paper reviews missing data methodology used in RCT-based cost-effectiveness analyses since 2003. Complete case analysis, which may lead to inappropriate conclusions, is still the most popular approach and its use has increased with time. The degree of missing data in cost-effectiveness analyses was often poorly reported and the methodology was often unclear. Reporting of missing data sensitivity analyses would improve article transparency.