Snoring, Sleep Apnoea and Cardiovascular Risk Factors: The MONICA II Study

The objective of this study was to evaluate the cardiovascular risk profile in self-reported snorers and sleep apnoeics in an adult representatively-selected population. A total of 1504 males and females, aged 30, 40, 50 and 60 years were in cluded. The following were measured: snoring, alcohol and tobacco consumption by questionnaire, blood pressure, serum high density lipoprotein (HDL) and total cholesterol. Nocturnal respiration was determined in 748 participants. Respiratory distress index (RDI) was defined as the number of apnoea and hypopnoea lasting longer than 10 seconds per hour sleep. Habitual snoring was reported by 19.1% (9.2–24.2%, aged 30–60 years) of males and 7.9% (3.8–11.7%, age 30–60 years) of females. An RDI ≥5 was found in 10.9% (7.1–18.3%, age 30–60 years) of males and in 6.3% (5.3–7.6%, age 30–60 years) of females. The following factors ware associated with snoring: age (P<0.02), sex (P<0.001), body mass index (BMI) (P<0.0001), alcohol (P<0.05) and tobacco (P<0.01) consumption. An RDI ≥5 was associated with sex (P<0.001), age (P<0.05), BMI (P<0.0001), tobacco (P<0.02) and alcohol (P<0.05) consumption. Self-reported snorers showed higher systolic (P<0.001) and diastolic (P<0.001) blood pressure and total cholesterol (P<0.001) and a lower HDL (P<0.001). The participants with RDI ≥5 showed higher systolic and diastolic blood pressure (P<0.001) and total cholesterol (P<0.001). Significant correlations ware found between BMI and blood pressure (P<0.0001), total cholesterol (P<0.0001) and HDL (P<0.0001). The relation between RDI, self-reported snoring, blood pressure and HDL-cholesterol became non-significant in the multivanate analysis when age, sex, BMI, alcohol and tobacco consumption were taken into account. We conclude that snoring and sleep apnoea are associated with major cardiovascular risk factors, including BMI, alcohol and tobacco consumption. The relation between snoring, sleep apnoea and blood pressure was not significant when controlling for BMI. Sufficient control of the confounders is thus essential in studies on snonng, obstructive sleep apnoea and the risk of cardiovascular diseases.