The prevalence of exercise-induced bronchoconstriction in non-asthmatic swimmers: A systematic review and meta-analysis

Abstract

Objective: To evaluate the prevalence of exercise-induced bronchoconstriction (EIB) in non-asthmatic swimmers. Methods: We searched BVS/LILACS, MEDLINE/PubMed, Web of Science, Scopus, SPORTDiscus databases, and two repositories (BDTD and OATD) up to July 2023. A combination of MeSH descriptors and text words were used. We selected original studies reporting cases of EIB diagnosed by objective test in non-asthmatic swimmers. We assessed the quality of the included studies for bias with Joanna Briggs checklist for prevalence, and conducted random-effects meta-analyses with planned subgroup analysis. Results: This review retrieved 33 studies (700 non-asthmatics swimmers, 250 cases of EIB). The EIB prevalence was 34% (95% CI: 25-45%) with a significant heterogeneity (I2 = 68%), which was partially explained by the subgroup analysis for diagnostic method used. The methacholine test showed a higher prevalence (51%, 95% CI: 43-59%) with a low heterogeneity (I2 = 28%). Only three studies (90.1%) were considered as low risk of bias, while the remaining 30 (90.9%), as moderate. The results indicate that non-asthmatic swimmers have an expressive prevalence of EIB, especially when performing methacholine test. Conclusion: The better understanding of the prevalence of EIB among non-asthmatic swimmers, estimated in 34% in this review, should be considered a warning to professionals involved in training and health policymakers. Public health interventions for prevention are required. Also, the substantial heterogeneity between studies highlights the need for better designed studies.