P049 Prevalence and Predictors of Comorbid Insomnia and Obstructive Sleep Apnoea in Chinese and Caucasian Patients

Abstract Introduction Insomnia and obstructive sleep apnoea (OSA) often co-occur as co-morbid insomnia and obstructive sleep apnoea (COMISA). Despite having a comparable prevalence of OSA with Caucasians, Chinese patients have a distinct OSA phenotype that is less dependent on obesity. However, to date, no studies have investigated COMISA in this population. This study investigated the prevalence and predictors of COMISA in an ethnically diverse clinically referred population for investigation of sleep disordered breathing. Methods Data from 183 patients (27 Chinese, 156 Caucasian) undergoing in-laboratory diagnostic polysomnography were reviewed. COMISA was defined as an apnoea-hypopnea index (AHI) >5 events/hour and an Insomnia Severity Index (ISI) score ≥15. Multivariable logistic and linear regression analyses were carried out on demographic and polysomnographic variables to determine predictors of COMISA and their associations with ISI respectively. Results Despite a similar prevalence of OSA (Caucasian 84.0% vs Chinese 81.5%, p=n.s.), Chinese participants showed significantly higher rates of insomnia (77.8% vs 41.3%, p<0.001) and COMISA (59.3% vs 34.7%, p=0.028) than Caucasians. For Caucasians, Arousal Index (OR: 1.04, p=0.003) and Depression (OR: 1.15, p=0.019) were both significant predictors of COMISA. For Chinese participants, no predictors of COMISA were identified, however both Sleep Onset Latency (SOL) (B=-0.198, p=0.029) and AHI (B=-0.150, p=0.020) inversely predicted ISI. Conclusion In our clinical population, COMISA was more prevalent among Chinese patients, driven by a higher incidence of insomnia. Future research should focus on determining the relative contribution of ethnic physiological differences and immigratory stress to the potential existence of a distinct Chinese COMISA phenotype.