Davies SE, et al. - Researchers assessed the strength of the link between bronchial asthma and obstructive sleep apnoea (OSA), as well as the influence of OSA on asthma-related clinical outcomes. They identified studies up to and including 2016 from EMBASE and MEDLINE databases. For this analysis, they selected studies that involved asthmatics, and that used either polysomnography or validated questionnaires such as the Sleep Apnoea Scale of the Sleep Disorders Questionnaire (SA-SDQ), STOP BANG or the Berlin questionnaire to report a prevalence of OSA. Of 19 identified studies, the inclusion/exclusion criteria were fulfilled by 13 questionnaire-based studies. A high prevalence of OSA in asthma was reported; this was observed especially within severe asthma populations. Worse clinical outcomes were reported in relation to co-diagnosis of OSA in asthma patients. However, this outcome was not consistent and only a small number of studies used polysomnography to corroborate OSA.