Characteristics of included studies
| Characteristic | n=184 | Min, max | |
| Median | (IQR) | ||
| Sample size | 556 | (281, 1704) | 30, 205 513 |
| Centres* | 35 | (12, 100) | 1, 1368 |
| Trial duration (weeks)† | 52 | (24, 104) | 0.3, 521 |
| n | % | |
| Journal | ||
| BMJ | 3 | 1.6 |
| JAMA | 81 | 44.0 |
| Lancet | 38 | 20.7 |
| NEJM | 62 | 33.7 |
| Funded by | ||
| Public | 70 | 38.3 |
| Industry | 80 | 43.7 |
| Both | 33 | 18.0 |
| Centre | ||
| Single centre | 12 | 7.0 |
| Multicentre | 161 | 93.0 |
| Control | ||
| Placebo | 95 | 51.6 |
| Active | 80 | 43.5 |
| Both | 8 | 4.4 |
| Neither‡ | 1 | 0.5 |
*Eleven reports did not specify the number of centres.
†Two reports did not specify trial duration.
‡One trial compared interventional drug to behavioural change intervention.
JAMA, Journal of the American Medical Association; max, maximum; min, minimum; NEJM, New England Journal of Medicine.