Analysis of clinical trials
[3][4] Randomized clinical trials analyzed by the intention-to-treat (ITT) approach provide fair comparisons among the treatment groups because it avoids the bias associated with the non-random loss of the participants.[5][6] The basic ITT principle is that participants in the trials should be analysed in the groups to which they were randomized, regardless of whether they received or adhered to the allocated intervention.[5] However, medical investigators often have difficulties in accepting ITT analysis because of clinical trial issues like missing data or adherence to protocol.The advantages to the LOCF approach are that: However, the National Academy of Sciences, in an advisory report to the Food and Drug Administration on missing data in clinical trials, recommended against the uncritical use of methods like LOCF, stating that "Single imputation methods like last observation carried forward and baseline observation carried forward should not be used as the primary approach to the treatment of missing data unless the assumptions that underlie them are scientifically justified.As the 1998 International Conference on Harmonization E9 Guidance on Statisticial Principles for Clinical Trials noted, "Unfortunately, no universally applicable methods of handling missing values can be recommended.