An assessment of oxidized LDL in the lipid profiles of patients with obstructive sleep apnea and its association with both hypertension and dyslipidemia, and the impact of treatment with CPAP

Objective: Obstructive sleep apnea (OSA) has been linked to increased oxidative stress, lipid peroxidation and worsening atherosclerosis. This study investigated oxidized low-density lipoprotein (oxLDL) as a marker of lipid peroxidation, and total LDL cholesterol (direct LDL-C), as a marker of the lipid profile among individuals with OSA, and its association with hypertension (HYP) and dyslipidemia (DYS). The impact of one year of continuous positive airway pressure (CPAP) was also assessed. Methods: Blood was collected after 12 h of fasting from 99 consecutive patients who were diagnosed with OSA via polysomnography, and were also diagnosed with both HYP and DYS via clinical and laboratory studies. The patients were classified into the following three groups: GI [OSA with comorbidities (HYP or DYS)], GII [OSA without comorbidities], and GIII [control]. Thirty-five patients with an apnea/hypopnea index >20 per hour of sleep were randomized to groups that received either Sham-CPAP or CPAP treatments over 12 months. Results: In a binary regression controlled for sex, age, body mass index, and glycemia, model 1 which analyzed direct LDL-C, demonstrated significant levels of risk in the setting of DYS but not in the settings of HYP and OSA. In model 2, which analyzed oxLDL, DYS (p = 0.01), HYP (p = 0.032), and OSA (p = 0.039) were statistically significant. Significant alterations were observed in only the sleep parameters following one year of CPAP. Conclusions: Based on the statistical regression model, only the presence of DYS (p = 0.001) was associated with the levels of direct LDL-C. The remaining comorbidities (OSA and HYP) were not significantly related to the levels of direct LDL-C. Regarding oxLDL, OSA, HYP and DYS each added significant score values to the levels of oxLDL. These findings are suggestive of the importance of assessing oxLDL among patients presenting with OSA, both with and without comorbidities. (C) 2015 Elsevier Ireland Ltd. All rights reserved.