Seventeen RCTs were included (n=1,133; 470 adults and 663 children).
Jadad scores for quality ranged from 3 points (7 RCTs) to 5 points (4 RCTs) out of a possible maximum of 5. All of the trials were double-blinded.
A significantly lower rate of hospital admission was reported in patients treated with ICS than those receiving placebo or SCS (OR 0.55, 95% CI: 0.35, 0.88; 7 studies), but there was evidence of significant statistical heterogeneity (p=0.005; I-squared 67.7%). A greater reduction in admission rate, favouring the ICS group, was reported for trials using multiple doses of ICS (OR 0.30, 95% CI: 0.16, 0.55; 5 studies); no statistical heterogeneity was reported. When the analysis was restricted to studies comparing ICS versus SCS, the results were mixed: 2 studies comparing multiple doses of ICS with SCS reported no statistically significant difference between the groups (OR 0.43, 95% CI: 0.14, 1.28), while a third study using a single dose of ICS reported statistically significant results favouring the SCS group (OR 3.91, 95% CI: 1.31, 11.71). The author speculated that the heterogeneity between these studies was due to differences in dosing (single versus multiple) and the timing of the outcome measure.
Significantly more patients treated with ICS were discharged from the emergency department compared with those who received placebo or SCS (OR 4.70, 95% CI: 2.97, 7.42; 6 studies); there was no evidence of statistical heterogeneity.
A statistically significant improvement in PEF was noted in patients treated with ICS compared with those who received placebo (p<=0.0001) or SCS (p<=0.001), with pooled results (7 studies) showing weighted mean differences of 25, 35 and 46 L/minute at 1, 2 and 3 hours, respectively. There was a dose-response relationship, with greater benefit in patients receiving multiple doses of ICS. These results had low to moderate heterogeneity (I-squared: 0 to 38%). Measures of FEV1 produced similar results, with statistically significant benefits in the ICS group versus either placebo or SCS at the 2 and 3 hour time points (p<=0.001). However, the results for outcomes at 1 hour were mixed, with a high level of heterogeneity (I-squared: 82 to 95%).
All studies reported that there were no serious side-effects among the participants.
Further analyses were reported in the review.