Obstructive sleep apnoea/hypopnea influences high-density lipoprotein cholesterol in the elderly

An association between obstructive sleep apnoea/hypopnea (OSAH) and cardiovascular risk factors such as dyslipidemia has been described in adults and high-risk populations.

We examined this association in a prospective cohort (SYNAPSE study) of 846 elderly (68.5+/-1.1 years) volunteers (41.6% of men). No subject presented with recognized OSAH syndrome, heart disease, or any neurological disorder. Unattended at-home polygraphy was done by all subjects. OSAH severity was defined as moderate (apnoea/hypopnea index: AHI>15/h) or severe (AHI>30/h). High-density lipoprotein cholesterol (HDL-c) was measured by immuno-separation-based homogenous assay.

The prevalence of severe cases reached 21.5% (AHI mean+/-SD: 43.5+/-11.9). Using univariate linear regression analysis, AHI (R=-0.172; p<0.0001), oxyhemoglobin desaturation index (ODI) (R=-0.108; p<0.002), mean SaO(2) (R=0.125; p<0.0003) and Nadir SaO(2) (R=0.094; p<0.007) were significantly associated with HDL-c. Multiple regression analysis demonstrated that male gender, BMI, waist to hip ratio, ODI, and AHI represent independent predictors of HDL-c. Logistic regression analysis showed a significant association between severe OSAH and low HDL-c serum levels (p<0.03) after adjustment for gender, BMI, hypertension, glycaemia, waist to hip ratio, alcohol intake and treated dyslipidemia. The association appears more evident in subjects free of lipid-lowering medications and beta-blockers (p<0.007). There was no independent association of OSAH syndrome with low-density lipoprotein (LDL) cholesterol.

Unrecognized moderate to severe apnoea/hypopnea syndrome was independently associated with low HDL-c serum levels in the present cross-sectional based elderly population. This could explain the deleterious effect of OSAH syndrome on cardiovascular risk.