Inhaled corticosteroids and risk of influenza in patients with asthma: a meta-analysis of randomized controlled trials

Background It was reported that inhaled corticosteroids (ICS) treatment may affect local immunity and microbial community of the airway. However, whether ICS treatment increases the risk of influenza in patients with asthma remains unclear. This meta-analysis aimed to compare the risk of influenza between ICS and non-ICS treatment in patients with asthma. Methods PubMed, Embase, Cochrane Library and Clinical Trials.gov were searched from inception until November 2019. Randomized controlled trials (RCTs) were included that compared ICS treatment with non-ICS treatment on the risk of influenza in patients with asthma. Meta-analyses were conducted by the Peto approach and Mantel–Haenszel approach with corresponding 95% CIs. Results Nine trials involving 6486 patients were included in this meta-analysis. The risk of influenza was not different between ICS treatment and the control groups (Peto OR: 1.01, 95% CI 0.74–1.37, P = 0.95). The results of subgroup analyses based on durations (long-term and short-term treatment), doses (high-, medium- and low-dose treatment) and types (fluticasone and budesonide treatment) of ICS were consistent with the above pooled results. Moreover, subgroup analysis based on patients’ age also revealed that use of ICS did not increase the risk of influenza. Results of the two meta-analysis approaches were similar. Conclusions Use of ICS does not increase the risk of influenza in patients with asthma. This study adds to safety evidence of ICS as a regular controller treatment for patients with asthma.