Sixteen RCTs were included in the review. Groups in included studies ranged from 18 to 150 patients with a mean study group size of 61 patients.
Methodological quality scores ranged from 0.30 to 0.92 (mean 0.55). The inter-rater K-agreements for study selection and validity assessment were 0.81 and 0.89 respectively.
The funnel plot statistical assessment indicated the absence of bias associated with sample size.
At the 3-hour assessment, only high doses of inhaled corticosteroids (CCSs) significantly improved pulmonary function compared with placebo (ES = 0.56, 95% CI: 0.15, 0.97). After receiving IV CCSs, patients required at least 6 to 24 hours to show moderate but nonsignificant improvements of pulmonary function: 6-hour ES = 0.44, 95% CI: -0.01, 0.89; 12-hour ES = 0.54, 95% CI: -0.08, 1.17; and 24- hour ES = 0.53, 95% CI: -0.39, 1.45).
The data from 6 studies used for admission rate outcome showed a 32% reduction in favour of the use of IV CCSs (RR = 0.68, 95% CI: 0.47, 0.99; NNT = 12.5, 95% CI: 7.1, 50). However, the pooled effect of the 3 high-quality studies showed no difference between groups (RR = 1.21, 95% CI: 0.67, 2.18).
Oral CCSs provided a similarly beneficial effect on pulmonary function when compared with parenteral administration (ES = -0.14, 95% CI: -0.82, 0.31).
The results showed a nonsignificant favourable trend toward improved outcome with medium or high doses of CCSs.