Descriptive information for the 11 trials
| First author [ref no.] | Subjects n | F:M | Age mean±sd (range) | Duration of asthma yrs mean (range) | Blindness | Duration of treatment days | Excluded patients n | Medication | Outcome measures reported |
| Chow 25 | 16 | 11 (8–13) | SB | 21 | 0 | Yes | FEV1 | ||
| Christensen 2 | 17 | 11:6 | 32.2 (19–48) | DB | 35 | 0 | Not clear | PEFR | |
| Dias 6 | 20 | 9:11 | 41.6±15 (18–73) | DB | 21.7 | 0 | Yes | PEFR | |
| Fung 26 | 19 | (9–13.5) | SB | 0 | Yes | FEV1/FVC/PEFR | |||
| Luu 27 | 17 | 11:6 | 31±11 (19–61) | 16 (2–51) | DB | 11 | 0 | Not clear | VC/PEFR |
| Mitchell 1 | 31 | 13:18 | 29 (15–55) | 23 (5–38) | SB | 29 | 5 | Yes | PEFR |
| Morton 28 | 13 | 13:0 | (17–27) | DB | 35 | 0 | Yes | FEV1 | |
| Tandon 24 | 15 | 6:9 | 40.5 (19–57) | (5–34) | DB | 35 | 0 | Yes | PEFR/FEV1/FVC/ |
| Tandon 29 | 16 | 6:10 | 39.1±16 (11–60) | 19.62 (2–49) | DB | 3 | 0 | Yes | FEV1 |
| Tashkin 30 | 12 | 10:2 | 43±11 (16–64) | 21.83 (1–45) | DB | 3 | 0 | Yes | FVC/FEV1/FEF |
| Tashkin 23 | 26 | 16:10 | 34±18.59 (8–73) | 21.28 (2–59) | DB | 28 | 1 | Yes | FVC/FEV1 |
M: male
F: female
SB: single-blind
DB: double blind
FEV1: forced expiratory volume in one second
FEF: forced expiratory flow
PEFR: peak expiratory flow rate
VC: vital capacity
FVC: forced vital capacity
In all 11 trials the randomisation method was unknown