Luyster et al investigated the association between obstructive sleep apnea (OSA) and the presence of coronary artery calcium (CAC) in inhabitants with a mean age of 61 years without cardiovascular disease, stratified by body mass index (BMI). Obesity is a risk factor of sleep apnea, and CAC is a marker of subclinical coronary disease. The presence of CAC was defined as an Agatston score >0, and adjusted odds ratios (ORs; 95% confidence intervals [CIs]) of apnea–hypopnea index (AHI) ≥15 for the presence of CAC was 2.33 (1.01 to 5.38) and 1.71 (0.71 to 4.13) by excluding and including BMI as an adjusting variable, respectively. Although the authors concluded that OSA was independently associated with early atherosclerotic plaque burden in nonobese patients, there was no significant association between AHI score and the presence of CAC in both groups stratified by BMI. I have some concerns on their study.

The authors cited the following 2 articles: Kim et al demonstrated that OR (95% CI) of severe OSA in men in their 40s for the presence of CAC after adjusting for confounding factors excluding BMI was 2.21 (1.01 to 4.86), although the significance disappeared by including BMI as an adjusting variable; Matthews et al also concluded that CAC was not associated with AHI, independent of BMI. In contrast, Lutsey et al recently conducted a multiethnic study, and severe OSA was significantly associated with subclinical coronary artery disease, independent of obesity and traditional cardiovascular risk factors. The level of significance of the article by Lutsey et al existed at borderline, and the significance disappeared when the greater cutoff value of CAC was adopted. Furthermore, Kim et al reported male data with early middle generation and adjusted ORs (95%CIs) of overweight (BMI 23 to 27.4) and obesity (BMI ≥27.5) for the presence of CAC were 4.13 (1.86 to 9.19) and 15.1 (4.63 to 49.3) by including AHI as an adjusting variable, respectively. Taken together, the contribution rate of BMI to CAC is stronger than that of AHI in their study. I suppose that direct association between OSA and the presence of CAC has not yet been adequately determined.