Obstructive sleep apnoea and cardiovascular events in a Chinese population

Abstract

Introduction: Although several clinical and epidemiological studies have reported an association between obstructive sleep apnoea (OSA) and cardiovascular (CV) events, the results and magnitude remain unclear and inconsistent. We hence propose to evaluate the role of OSA on the incidence of composite CV events in a Chinese cohort. Methods: The eligible cohort was drawn from those who received sleep studies between 1 January 2007 and 31 December 2010 in the Department of Medicine, Queen Mary Hospital. Follow-up data were drawn from the Hospital Authority Clinical Management System up to the day of data entry in this study. Apnoea-hypopnoea index (AHI) from automated scoring of polysomnogram was used in the Cox regression model, controlling for age, gender, waist circumference, daytime sleepiness, and comorbidities. Results: Overall, 158 (14.4%) of 1099 subjects experienced composite CV outcomes over a median followup of 85 months, giving an incident rate around 2.1 per 100 person-years. In both univariate and multivariate models, there was no significant association between AHI and CV events. While waist circumference was an independent and significant predictor, which indicated that obesity is always in the close partnership between OSA and CV events. This analysis has not yet taken into account the influence of OSA treatment and manually scored sleep data. Conclusion: Beyond the obesity, OSA per se would not aggravate the CV outcomes. Other OSA-related variables should be considered in further studies.