Table 1 Characteristics of the 23 included trials
Characteristics | Number of articles | Missing data | |
|---|---|---|---|
N (%) | N (%) | ||
Publication date | Before 2009 | 14 (61) | 0 |
After 2009 | 9 (39) | ||
Countrya | China | 2 (9) | 1 (4) |
US | 5 (22) | ||
UK | 4 (17) | ||
Denmark | 3 (13) | ||
Netherlands | 2 (9) | ||
Canada | 2 (9) | ||
Japan | 1 (4) | ||
New Zealand | 1 (4) | ||
Swiss | 2 (9) | ||
Finland/Norway | 1 (4) | ||
Greece | 2 (9) | ||
Design | Two parallel groups | 19 (83) | 0 |
Three parallel groups | 3 (13) | ||
Double factorial design 2 × 2 | 1 (4) | ||
Sample size median (Q1; Q3) | 179 (82; 1068) | 0 | |
Number of centres | Monocentric studies | 10 (45) | 4 (17) |
Pluricentric studies | 12 (55) | ||
Number of centres, median (Q1; Q3) | 14 (1; 40) | ||
Follow-up in months, median (Q1; Q3) | 51 (6; 67) | 1 (4) | |