Abstract
BACKGROUND: Allergic rhinitis and asthma are mediated by similar allergic mechanisms. They may represent two manifestations of the same united airway disease and therefore intranasal corticosteroids (INCS) could improve asthma. Nevertheless none of the asthma guidelines have advocated intranasal corticosteroids for asthma. OBJECTIVES: To assess the efficacy of intranasal corticosteroids on asthma outcomes in people with rhinitis and asthma. SEARCH STRATEGY: We searched the Cochrane Airways Group trials register, the Cochrane Central Register of Controlled Trials (Issue 1, 2003), MEDLINE and reference lists of articles. We also contacted researchers in the field. Last search updated in March 2003. SELECTION CRITERIA: Randomised controlled trials comparing intranasal corticosteroids to intranasal placebo or to other traditional asthma treatments were included. Intrabronchial corticosteroids were not allowed but a device combining intranasal and intrabronchial corticosteroid was considered as being a primary INCS technique and was therefore also compared to placebo. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. Quality assessment for the 14 eligible studies was performed using the Jadad score and by ranking allocation concealment. Statistical analysis for continuous data was done by weighted mean difference or standardised mean difference. MAIN RESULTS: Fourteen trials involving 477 people were included. Meta-analysis for asthma outcomes failed to show a statistically significant benefit of INCS in asthma. However, for symptom scores and forced expiratory volume in one second, the trend favoured a beneficial effect of INCS. For asthma symptom scores (two parallel studies), the standardised mean difference was 0.61 (95% confidence interval (CI) -0.04 to 1.26). Meta-analysis for forced expiratory volume in one second (five parallel studies) gave a standardised mean difference of 0.31 (95% CI -0.04 to 0.65). In the parallel studies, meta-analysis of peak expiratory flow gave a standardised mean difference of -0.10 Litres/min (95% CI -0.55 to 0.35) for mean peak flow (three studies). Meta-analysis for methacholine airway responsiveness (three parallel studies) showed a standardised mean difference of -0.20 (-95% CI 0.64 to 0.24). REVIEWER'S CONCLUSIONS: Intranasal corticosteroids were well tolerated. While INCS tended to improve asthma symptoms and forced expiratory volume in one second, the results did not reach significance. The combination of intranasal plus intrabronchial corticosteroids should remain the current clinical practice until more research is done.