Table 2 Trial characteristics
From: A review of the handling of missing longitudinal outcome data in clinical trials
| Â | Â | Method of handling missing data | Acceptable method?1 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Â | Â | No. of papers | Complete cases | Simple2 | Multiple | Mixed models | No missing data | Unclear | Other3 | Yes | No | Unclear |
Number of patients | 1-100 | 48 | 17 | 8 | 0 | 4 | 8 | 3 | 8 | 18 | 9 | 13 |
| Â | 101-200 | 22 | 8 | 2 | 2 | 5 | 1 | 0 | 4 | 9 | 11 | 1 |
| Â | 201-300 | 12 | 4 | 2 | 0 | 4 | 0 | 0 | 2 | 8 | 4 | 0 |
| Â | 301-400 | 7 | 1 | 1 | 1 | 1 | 0 | 0 | 3 | 3 | 3 | 1 |
| Â | 400+ | 11 | 1 | 1 | 1 | 4 | 0 | 0 | 4 | 6 | 3 | 2 |
Country of publication | USA | 53 | 20 | 7 | 2 | 10 | 4 | 0 | 10 | 20 | 18 | 11 |
| Â | UK | 40 | 8 | 6 | 2 | 7 | 3 | 3 | 11 | 20 | 12 | 5 |
| Â | Denmark | 3 | 2 | 0 | 0 | 0 | 1 | 0 | 0 | 2 | 0 | 0 |
| Â | Netherlands | 3 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 2 | 0 | 1 |
| Â | Japan | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
Number of time points | 3 | 38 | 13 | 4 | 3 | 10 | 1 | 1 | 6 | 14 | 16 | 7 |
| Â | 4 | 28 | 9 | 4 | 1 | 4 | 2 | 2 | 6 | 14 | 4 | 8 |
| Â | 5 | 16 | 4 | 3 | 0 | 3 | 2 | 0 | 4 | 10 | 3 | 1 |
| Â | 6 | 6 | 2 | 0 | 0 | 0 | 2 | 0 | 2 | 1 | 3 | 0 |
| Â | 7 | 4 | 1 | 0 | 0 | 0 | 2 | 0 | 1 | 1 | 1 | 0 |
| Â | 8+ | 8 | 2 | 3 | 0 | 1 | 0 | 0 | 2 | 4 | 3 | 1 |
Year | 2005-06 | 19 | 9 | 2 | 0 | 1 | 2 | 1 | 4 | 7 | 4 | 6 |
| Â | 2007-08 | 27 | 8 | 3 | 0 | 5 | 4 | 0 | 7 | 11 | 10 | 2 |
| Â | 2009-10 | 25 | 7 | 3 | 1 | 4 | 3 | 1 | 6 | 9 | 8 | 5 |
| Â | 2011-12 | 29 | 7 | 6 | 3 | 8 | 0 | 1 | 4 | 17 | 8 | 4 |
Clinical area | Mental health | 13 | 2 | 4 | 2 | 1 | 1 | 1 | 2 | 7 | 2 | 3 |
| Â | Cancer | 11 | 4 | 1 | 1 | 4 | 0 | 1 | 0 | 5 | 4 | 2 |
| Â | Rheumatology | 10 | 4 | 1 | 0 | 2 | 1 | 0 | 2 | 3 | 5 | 1 |
| Â | Infectious diseases | 8 | 4 | 1 | 0 | 1 | 1 | 0 | 1 | 4 | 2 | 1 |
| Â | Heart and circulation | 7 | 1 | 2 | 0 | 1 | 0 | 0 | 3 | 3 | 2 | 2 |
| Â | Dentistry/oral health | 6 | 3 | 1 | 0 | 0 | 2 | 0 | 0 | 3 | 1 | 0 |
| Â | Neurology | 6 | 2 | 0 | 0 | 2 | 0 | 0 | 2 | 2 | 2 | 2 |
| Â | Anaesthesia and pain | 6 | 3 | 0 | 0 | 1 | 0 | 0 | 2 | 2 | 2 | 2 |
| Â | Other4 | 33 | 8 | 4 | 1 | 6 | 4 | 1 | 9 | 15 | 10 | 4 |
Dropout reasons recorded? | Yes | 35 (39.8%)5 | 15 | 7 | 0 | 7 | NA | NA | 6 | 20 | 11 | 4 |
| Â | Partial information | 25 (28.4%) | 7 | 5 | 1 | 7 | NA | NA | 5 | 15 | 9 | 1 |
| Â | No | 28 (31.8%) | 10 | 2 | 3 | 4 | NA | NA | 9 | 9 | 10 | 9 |