BACKGROUND: In randomised trials of medical interventions, the most reliable analysis follows the intention-to-treat (ITT) principle. However, the ITT analysis requires that missing outcome data have to be imputed. Different imputation techniques may give different results and some may lead to bias. In anti- @entity28 drug trials, many data are usually missing, and the most used imputation method is last observation carried forward (LOCF). LOCF is generally considered conservative, but there are more reliable methods such as @entity156 ( @entity156 ). OBJECTIVES: To compare four different methods of handling missing data in a 60-week placebo controlled anti- @entity28 drug trial on @entity1771 . METHODS: We compared an analysis of complete cases with datasets where missing body weight measurements had been replaced using three different imputation methods: LOCF, baseline carried forward (BOCF) and @entity156 . RESULTS: 561 @entity1 were randomised. Compared to placebo, there was a significantly greater weight loss with @entity1771 in all analyses: 9.5 kg (SE 1.17) in the complete case analysis (N=86), 6.8 kg (SE 0.66) using LOCF (N=561), 6.4 kg (SE 0.90) using @entity156 (N=561) and 1.5 kg (SE 0.28) using BOCF (N=561). CONCLUSIONS: The different imputation methods gave very different results. Contrary to widely stated claims, LOCF did not produce a conservative (i.e., lower) efficacy estimate compared to @entity156 . Also, LOCF had a lower SE than @entity156 .

Comparison of results from different imputation techniques for missing data from an anti- XXXX drug trial.

@entity1 :: ('9606', 'Species') :: ['participants'] @entity1771 :: ('MESH:C052342', 'Chemical') :: ['topiramate'] @entity156 :: ('MESH:D000015', 'Disease') :: ['MI', 'multiple imputation'] @entity28 :: ('MESH:D009765', 'Disease') :: ['obesity']
@entity28 :: (MESH:D009765,Disease) :: ['obesity']
