Reported versus actual intention-to-treat practices
| Reported using ITT | Conducted true ITT* | Sample analysed | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Full random sample | Full random sample (likely) | Random sample FU | Sufficient dose | Completer sample | False inclusion | Other | Unclear | Total number of ITT and/or non-ITT approaches used | ||
| No (K=91) | 32 (35%) | 28 (25%) | 4 (4%) | 6 (5%) | 19 (17%) | 31 (28%) | 2 (2%) | 4 (4%) | 16 (14%) | 112 |
| Yes (K=74) | 29 (39%) | 21 (21%) | 9 (9%) | 7 (7%) | 40 (39%) | 7 (7%) | 8 (8%) | 2 (2%) | 0 (0%) | 102 |
| Total (K=165) | 61 (37%) | 49 (23%) | 13 (6%) | 13 (6%) | 59 (28%) | 38 (18%) | 10 (5%) | 6 (3%) | 16 (8%) | 214* |
*ITT is the full random sample or full random sample (likely) categories; K is the study, column description: (1) full random sample (analyses involved the total randomised N's), (2) full random sample (likely; appears to be using the full randomised sample, but N's are not reported with analyses), (3) random sample followed up (attempted to follow-up all randomised participants regardless of the amount of medication/treatment completed, and conducted analyses on this sample), (4) sufficient dose (analyses conducted on only those participants who received a minimum amount of medication/treatment), (5) completer sample (analyses conducted on only those patients who completed the medication/treatment phase), (6) false inclusion (after randomisation, participant is found to not meet the inclusion criteria and is subsequently removed from the analyses), (7) other (analyses report N's or degrees of freedom that are less than what would be expected for the randomised N, but no explanation on the participants included or excluded from the analysis is provided) and (8) unclear (insufficient information to determine the sample analysed). Only categories (1) full random sample and (2) full random sample (likely) are considered a ‘true’ ITT strategy, whereas the others are considered something other than ITT.
*The values in each row of table 1 do not sum to the total number of studies in the first column (ie, ‘Reported Using ITT’) due to the 45 studies utilizing ITT and non-ITT analyses (eg, conducted an ITT analysis assuming failure for dichotomous outcomes and also used a complete cases approach for continuous outcomes).
ITT, intention to treat.