Prevalence and clinical impact of Comorbid Insomnia and Sleep Apnoea (COMISA) in Severe Asthma patients

Background: Impaired sleep quality is frequent in asthma, especially in severe cases. Obstructive sleep apnoea (OSA) and insomnia are prevalent sleep disorders that often co-occur. Comorbid insomnia and sleep apnoea (COMISA) leads to greater impairments than either condition alone. This study aimed to assess the prevalence and clinical impact of OSA, insomnia and COMISA in patients with severe asthma and evaluate the diagnostic accuracy of screening questionnaires for OSA in this subpopulation. Methods: Cross-sectional study of adults with severe asthma recruited from a specialized clinic over a 6-month period. Asthma control was assessed using the Asthma Control Test (ACT), Mini Asthma Quality of Life Questionnaire (MiniAQLQ), Control of Allergic Rhinitis and Asthma Test (CARAT) and Global Initiative for Asthma (GINA) assessment of asthma symptom control. Participants completed the STOP-Bang Questionnaire (SBQ), Berlin Questionnaire (BQ) and Epworth Sleepiness Scale (ESS) to screen for OSA and underwent a Home Sleep Apnoea Test to confirm the diagnosis. Insomnia severity was assessed using the Insomnia Severity Index (ISI). Results: Among 61 patients (83.6% female, mean age 54.6 years), 42.6% had partly controlled and 36.1% had uncontrolled asthma. OSA was identified in 37 patients (36.1% mild, 19.7% moderate, 4.9% severe), with severity associated with older age (p <0.001), higher body mass index (p =0.008), greater neck circumference (p <0.001) and cardiovascular disease (p =0.010). The sensitivity and specificity of the screening questionnaires for OSA were 66.7% and 83.8% for the SBQ (high risk), 75.0% and 75.7% for the BQ and 54.2% and 59.5% for the ESS, respectively. Insomnia was present in 39 patients (63.9%), with greater severity inversely correlated with asthma control questionnaires, including lower ACT (p =0.038), MiniAQLQ (p <0.001) and CARAT (p =0.013) scores and higher GINA (p =0.030) scores. COMISA was diagnosed in 25 patients (41.0%) and was associated with greater neck circumference and depression. Conclusions: Sleep disturbances, particularly COMISA, were frequent and often undiagnosed in severe asthma, emphasising the need for systematic screening of these patients. The link between insomnia severity and poor asthma control highlights sleep quality as a key intervention target in patients with severe asthma.