Trial design and assessment characteristics of the 114 trials included in the review
| Items | No | % | Total | |
| Trial design | Parallel group | 102 | 87.2 | 114 |
| Factorial | 3 | 2.6 | ||
| Crossover | 0 | 0.0 | ||
| Other* | 9 | 7.7 | ||
| Number of arms | 2 | 83 | 70.9 | 114 |
| 3 | 21 | 17.9 | ||
| 4 | 5 | 4.3 | ||
| >4 | 5 | 4.3 | ||
| Clinical area | Mental health | 30 | 25.6 | 114 |
| Musculoskeletal | 28 | 23.9 | ||
| Obstetrics and gynaecology | 9 | 7.7 | ||
| Gastrointestinal | 7 | 6.0 | ||
| Respiratory | 5 | 4.3 | ||
| Stroke | 5 | 4.3 | ||
| Primary care | 4 | 3.4 | ||
| Cardiovascular | 4 | 3.4 | ||
| Cancer/oncology | 3 | 2.6 | ||
| Dermatology | 4 | 3.4 | ||
| Other† | 15 | 12.8 | ||
| Number of trials with a baseline assessment of the patient-reported outcome | 101 | 86.3 | 114 | |
| Timing of primary outcome postbaseline assessments | <1 month | 7 | 6.0 | 114 |
| 1–6 months | 28 | 23.9 | ||
| >6–18 months | 50 | 42.7 | ||
| >18 months | 27 | 23.1 | ||
| Missing‡ | 2 | 1.7 | ||
| Number of postbaseline assessments | 1 | 5 | 4.3 | 114 |
| 2 | 41 | 35.0 | ||
| 3 | 29 | 24.8 | ||
| 4 | 19 | 16.2 | ||
| >4 | 18 | 15.4 | ||
| Missing‡ | 2 | 1.7 |
*Patient preference/Zelen’s.
†Chronic fatigue, minor surgery, multiple sclerosis, neurosurgery, paediatric, sleep disorders, urology, vascular.
‡Two trials did not specify the timing and number of postbaseline assessments.