Missing data in the health related quality of life EQ-5D-3L instrument—should we impute individual domains or the actual index

Background Missing data is a known and considerable problem in outcome measures for economic evaluations. EQ-5D-3L is one of the most widely used outcome measure in the economic evaluation of health care technologies, and so far researchers have used different methods to deal with missing EQ-5D-3L data. Current evidence recommends multiple imputation (MI), but there is little guidance on whether MI should be carried out at domain level or index values.