Abstract: Eight primary studies, including 570 participants, were included. The overall methodological quality of studies was good. Significant clinical heterogeneity resulting from differences in participants and interventions, as well as variation in outcome measures, limited the validity of comparisons between studies for most outcomes. Data for the primary outcome of clinical cure or significant (> 70%) improvement were available for only three studies, which were too heterogeneous to pool. Similarly, heterogeneity in study characteristics limited the validity of meta-analysis for the secondary outcomes of proportion of participants with clinical cure or over 50% reduction in cough severity measure and clinical cure. One parallel group trial of chronic cough which identified a significant treatment effect contributed the majority of statistical heterogeneity for these outcomes. While ICS treatment resulted in a mean decrease in cough score of 0.34 standard deviations (SMD -0.34; 95% CI -0.56 to -0.13; 346 participants), the quality of evidence was low. Heterogeneity also prevented meta-analysis for the outcome of mean change in visual analogue scale score. Meta-analysis was not possible for the outcomes of pulmonary function, complications of cough or biomarkers of inflammation due to insufficient data. There was moderate quality evidence that treatment with ICS did not significantly increase the odds of experiencing an adverse event (OR 1.67; 95% CI 0.92 to 3.04). The studies were highly heterogeneous and results were inconsistent. Heterogeneity in study design needs to be addressed in future research in order to test the efficacy of this intervention. International cough guidelines recommend that a trial of ICS should only be considered in patients after thorough evaluation including chest X-ray and consideration of spirometry and other appropriate investigations.

Plain-language summary: We found eight studies on 570 people with cough lasting over three weeks. Studies included different types of participants in terms of age, duration of coughing and risk factors for cough. Studies also varied in types of ICS, doses, treatment lengths and types of inhaler used. Cough severity was measured using different scales. We looked at the proportion of people who were clinically cured or showed a significant improvement in cough severity as our primary outcome, but the data were too mixed to be able draw any conclusions. These differences between studies also prevented meaningful pooling of study results for proportion of people showing improvement in cough and average improvement in one specific type of cough scale. There was low quality evidence that ICS reduced cough severity score. There was not enough data about changes in pulmonary function, complications of cough and markers of inflammation to allow pooling of results.There was evidence of moderate quality that ICS treatment did not increase the risk of adverse events. This review has shown that the effects of ICS for subacute and chronic cough are inconsistent. Further studies with more consistent patient populations, interventions, outcome measures and reporting are needed to determine whether ICS help subacute and chronic cough in adults. This Cochrane plain language summary was written in December 2012.