Background: Systemic corticosteroid therapy is central to the management of acute asthma. The use of inhaled corticosteroids (ICS) may also be beneficial in this setting.
Objectives: To determine the benefit of ICS for the treatment of patients with acute asthma managed in the emergency department (ED).
Search methods: We identified controlled clinical trials from the Cochrane Airways Group specialised register of controlled trials. Bibliographies from included studies, known reviews, and texts also were searched. The latest search was September 2012.
Selection criteria: We included randomised controlled trials (RCTs) and quasi-RCTs. Studies were included if patients presented to the ED or its equivalent with acute asthma, and were treated with ICS or placebo, in addition to standard therapy. Two review authors independently selected potentially relevant articles, and then independently selected articles for inclusion. Methodological quality was independently assessed by two review authors. There were three different types of studies that were included in this review: 1) studies comparing ICS vs. placebo, with no systemic corticosteroids given to either treatment group, 2) studies comparing ICS vs. placebo, with systemic corticosteroids given to both treatment groups, and 3) studies comparing ICS alone versus systemic corticosteroids. For the analysis, the first two types of studies were included as separate subgroups in the primary analysis (ICS vs. placebo), while the third type of study was included in the secondary analysis (ICS vs. systemic corticosteroid).
Data collection and analysis: Data were extracted independently by two review authors if the authors were unable to verify the validity of extracted information. Missing data were obtained from the authors or calculated from other data presented in the paper. Where appropriate, individual and pooled dichotomous outcomes were reported as odds ratios (OR) with 95% confidence intervals (CIs). Where appropriate, individual and pooled continuous outcomes were reported as mean differences (MD) or standardized mean differences (SMD) with 95% CIs. The primary analysis employed a fixed-effect model and a random-effects model was used for sensitivity analysis. Heterogeneity is reported using I-squared (I(2)) statistics.
Main results: Twenty trials were selected for inclusion in the primary analysis (13 paediatric, seven adult), with a total number of 1403 patients. Patients treated with ICS were less likely to be admitted to hospital (OR 0.44; 95% CI 0.31 to 0.62; 12 studies; 960 patients) and heterogeneity (I(2) = 27%) was modest. This represents a reduction from 32 to 17 hospital admissions per 100 patients treated with ICS in comparison with placebo. Subgroup analysis of hospital admissions based on concomitant systemic corticosteroid use revealed that both subgroups indicated benefit from ICS in reducing hospital admissions (ICS and systemic corticosteroid versus systemic corticosteroid: OR 0.54; 95% CI 0.36 to 0.81; 5 studies; N = 433; ICS versus placebo: OR 0.27; 95% CI 0.14 to 0.52; 7 studies; N = 527). However, there was moderate heterogeneity in the subgroup using ICS in addition to systemic steroids (I(2) = 52%). Patients receiving ICS demonstrated small, significant improvements in peak expiratory flow (PEF: MD 7%; 95% CI 3% to 11%) and forced expiratory volume in one second (FEV(1): MD 6%; 95% CI 2% to 10%) at three to four hours post treatment). Only a small number of studies reported these outcomes such that they could be included in the meta-analysis and most of the studies in this comparison did not administer systemic corticosteroids to either treatment group. There was no evidence of significant adverse effects from ICS treatment with regard to tremor or nausea and vomiting. In the secondary analysis of studies comparing ICS alone versus systemic corticosteroid alone, heterogeneity among the studies complicated pooling of data or drawing reliable conclusions.
Authors' conclusions: ICS therapy reduces hospital admissions in patients with acute asthma who are not treated with oral or intravenous corticosteroids. They may also reduce admissions when they are used in addition to systemic corticosteroids; however, the most recent evidence is conflicting. There is insufficient evidence that ICS therapy results in clinically important changes in pulmonary function or clinical scores when used in acute asthma in addition to systemic corticosteroids. Also, there is insufficient evidence that ICS therapy can be used in place of systemic corticosteroid therapy when treating acute asthma. Further research is needed to clarify the most appropriate drug dosage and delivery device, and to define which patients are most likely to benefit from ICS therapy. Use of similar measures and reporting methods of lung function, and a common, validated, clinical score would be helpful in future versions of this meta-analysis.