Missing not at random in end of life care studies: multiple imputation and sensitivity analysis on data from the ACTION study.

Background: Missing data are common in end-of-life care studies, but there is still relatively little exploration of which is the best method to deal with them, and, in particular, if the missing at random (MAR) assumption is valid or missing not at random (MNAR) mechanisms should be assumed. In this paper we investigated this issue through a sensitivity analysis within the ACTION study, a multicenter cluster randomized controlled trial testing advance care planning in patients with advanced lung or colorectal cancer.

Methods: Multiple imputation procedures under MAR and MNAR assumptions were implemented.