Abstract
Background. Obstructive sleep apnea syndrome (OSAS) is associated with systemic inflammation and increased risk of cardiovascular and chronic kidney disease. Cystatin C (Cyst C) is a novel biomarker of both latent renal damage and cardiovascular disease. Aim of the study was to measure serum levels of Cyst C, as well as IL-8 and CRP, in otherwise healthy OSAS patients. Methods. 84 individuals examined with polysomnography for OSAS symptoms without known comorbidities were prospectively recruited. Results. According to apnea hypopnea index (AHI) subjects were divided in two groups: OSAS group (AHI > 5/hour, n = 64) and controls (AHI < 5/hour, n = 20), which were age- and BMI-matched. Cyst C levels were higher in OSAS patients versus controls (1176.13 ± 351.33 versus 938.60 ± 245.83 ng/mL, resp.; p = 0.017) while serum IL-8 and CRP levels did not differ significantly. Positive correlation was found between Cyst C levels and respiratory disturbance index (RDI) (r = 0.240, p = 0.039) and percentage of time with oxygen saturation <90% (r = 0.290, p = 0.02) and negative correlation was found between Cyst C levels and average oxygen saturation during sleep (r = −0.291, p = 0.012). After adjustment for age and BMI, RDI was the only independent predictor of Cyst C levels (β = 0.256, p = 0.039). Conclusion. Cyst C serum levels are increased in OSAS patients without comorbidities, suggesting an increased renal and cardiovascular disease risk.
Highlights
Obstructive sleep apnea syndrome (OSAS) is associated with systemic inflammation and increased risk of cardiovascular and chronic kidney disease
Serum Cys C levels were higher in OSAS patients compared with controls (1176.13±351.33 versus 938.60±245.83 ng/mL, resp., p = 0.017), while serum IL-8 levels and C-reactive protein (CRP) levels did no differ between groups (31.79 ± 20.09 versus 34.09 ± 14.37 pg/mL, p = 0.665 and 0.55 ± 0.57 versus 0.32 ± 0.41 mg/dL, p = 0.154, resp.)
The present study is the first one showing that serum Cystatin C (Cyst C) levels are elevated in middle-aged OSAS patients without known comorbidities, in comparison to age- and Body mass index (BMI)-matched healthy controls
Summary
Obstructive sleep apnea syndrome (OSAS) is associated with systemic inflammation and increased risk of cardiovascular and chronic kidney disease. Cyst C serum levels are increased in OSAS patients without comorbidities, suggesting an increased renal and cardiovascular disease risk. Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent episodes of upper airway collapse, resulting in oxygen desaturation and sleep fragmentation [1]. It is a highly prevalent disorder affecting approximately 10–17% of men and 3–9% of women; it often remains undiagnosed mainly due to lack of awareness and limited access to sleep laboratories [2]. OSAS may play an indirect role in the development and progression of CKD by sharing and exacerbating common risk factors such as arterial hypertension, diabetes mellitus, and obesity [14]
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