Severe Sleep Apnea Associated With Increased Systemic Inflammation and Decreased Serum Bilirubin

Obstructive sleep apnea hypopnea syndrome (OSAHS) among older men has been associated with increased systemic inflammation, as evidenced by an increased neutrophil/lymphocyte ratio (NLR) and provocation of coronary artery atherosclerosis, potentially resulting in myocardial infarction (MI). The total serum bilirubin levels (TSBLs; formed primarily from senescent red blood cells via the catabolic pathway in the reticuloendothelial system) at the higher end of the normal reference range are anti-inflammatory. However, at the lower end of the physiologic range, they have been associated with increased adverse vascular events. We compared the relationship between NLR and TSBL among subjects with "severe" OSAHS.

We used a retrospective, cross-sectional study design. The electronic medical records of older male subjects (age range, 55 to 74 years) with "severe" OSAHS treated by the dental service (January 1, 2017 to December 31, 2017) were examined. The predictor variable was the NLR, and the outcome variable was the TSBL; both were analyzed using continuous scales. Spearman's rank order correlation analysis explicated the relationship between the NLR and TBSL. Traditional proatherogenic risk factors (ie, age, body mass index, hypertension, hyperlipidemia, diabetes) were evaluated for independence using descriptive and logistic regression analysis. Significance was set at P = .05 for all tests.

A total sample size of 47 subjects (mean age, 63.74 ± 4.12 years) was enrolled in the present study. The Spearman rank order correlation analysis determined that the NLR is significantly (P = .038) and inversely related to the TSBL (r_s = -0.304).

Older men with "severe" OSAHS demonstrated an inverse relationship between NLR and TSBL. This combination of a heightened severity marker of systemic inflammation (ie, elevated NLR) and an indicator of amplified atherosclerotic activity (ie, diminished TSBL) will identify patients potentially at increased risk of future MI and the need for cardiovascular evaluation.