Table 4.
Reviews on missing data and ITT in the BMJ, JAMA, NEJM and the Lancet 1
| Study | Timing | Study inclusion criteria | Number of trials included | Number (%) of papers with missing data 2 | Number (%) of papers with more than 10% missing data 2 | Missing data approaches in primary analysis | Number (%) 3 | Number (%) of papers reporting sensitivity analysis 3 | Number (%) of papers reporting ITT 4 |
|---|---|---|---|---|---|---|---|---|---|
| Hollis et al., 1999 [2] | 1997 | All RCTs | 249 | 89/119 (75) | 29/119 (24) | Complete case | 44 (49) | 1 (1) | 119/249 (48) |
| Simple imputation | 15 (17) | ||||||||
| Multiple imputation | 0 | ||||||||
| Model based | 29 (33) | ||||||||
| Unclear | 1 (1) | ||||||||
| Wood et al., 2004 [22] | July-Dec, 2001 | All RCTs with non-survival outcomes | 71 | 63/71 (89) | 36/71 (51) | Complete case | 41 (65) | 13 (21) | 26/63 (41) |
| Simple imputation | 14 (22) | ||||||||
| Multiple imputation | 1 (2) | ||||||||
| Model based | 5 (8) | ||||||||
| Unclear | 2 (3) | ||||||||
| Gravel et al., 2007 [1] | 2002 | Sample of RCTs1 | 403 | 152/249 (61) | 52/249 (21) | Complete case | 89 (59) | Not reported | 249/403 (62) |
| Simple imputation | 32 (21) | 201/283 (71)5 | |||||||
| Multiple imputation | 1 (1) | ||||||||
| Model based6 | 0 | ||||||||
| Unclear6 | 30 (20) | ||||||||
| Fielding et al., 2008 [21] | 2005-2006 | Random sample of RCTs with Quality of life outcomes | 61 | 55/61 (90) | 22/61 (36) | Complete case | 30 (55) | 6 (11) | Not reported |
| Simple imputation | 11 (20) | ||||||||
| Multiple imputation | 1 (2) | ||||||||
| Model based | 9 (16) | ||||||||
| Unclear | 4 (7) | ||||||||
| Bell et al., (current study) | July-Dec, 2013 | All RCTS with non-survival outcomes | 77 | 73/77 (95) | 36/77 (47) | Complete case | 33 (45) | 27 (37) | 62/73 (85) |
| Simple imputation | 20 (27) | ||||||||
| Multiple imputation | 6 (8) | ||||||||
| Model based | 14 (19) |
1Gravel et al. reported on 10 journals, including the BMJ, JAMA, NEJM and the Lancet.
2Denominator is the number of trials included except for Hollis et al. and Gravel et al., where denominators are the number of papers reporting ITT.
3Denominator is the number of papers with missing data.
4Denominator is the number of papers with missing data except for Hollis et al. and Gravel et al. where denominators are the number of trials included in the review.
5Sub-analysis of RCTs from the four journals (BMJ, JAMA, NEJM and the Lancet) out of the 10 journals included in Gravel’s review.
6Three reported as “other” might be model based (added to 27 marked “unclear”).