Table 3 Subgroup analysis by timing of starting corticosteroid therapy
Timing of starting steroids | Number of studies | Number of patients | Relative risk (95% CI) | I2 |
|---|---|---|---|---|
Preventive therapy | Â | Â | Â | Â |
 Randomized controlled trials | 3 | 154 | 1.24 (0.57 to 2.72) | 80% |
Early ARDS (≤3 days) |  |  |  |  |
 Randomized controlled trials | 3 | 367 | 0.86 (0.71 to 1.04) | 17% |
 Cohort studies | 4 | 303 | 1.00 (0.24 to 4.20) | 70% |
Persistent ARDS (≥5 days) |  |  |  |  |
 Randomized controlled trials | 2 | 204 | 0.52 (0.11 to 2.52) | 79% |
 Cohort studies | 3 | 105 | 0.73 (0.44 to 1.23) | 0% |