Severe obstructive sleep apnea increases cystatin C in clinically latent renal dysfunction
Kota Kato1, Yoshifumi Takata, Yasuhiro Usui
1Department of Cardiology, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan.
Respiratory Medicine
|December 25, 2010
Summary
Severe obstructive sleep apnea (OSA) independently raises serum cystatin C levels in individuals without chronic kidney disease (CKD). Cystatin C may indicate underlying kidney dysfunction and cardiovascular risk linked to OSA.
Area of Science:
- Nephrology
- Cardiology
- Sleep Medicine
Background:
- Obstructive sleep apnea (OSA) is linked to increased cardiovascular disease (CVD) and chronic kidney disease (CKD) risk.
- Serum cystatin C is a prognostic biomarker for mortality and CVD, even in individuals without diagnosed CKD.
Purpose of the Study:
- To investigate the association between OSA severity and serum cystatin C levels in patients without CKD.
- To determine if severe OSA is an independent predictor of elevated cystatin C in this population.
Main Methods:
- A cross-sectional study included 267 OSA patients (apnea-hypopnea index [AHI] ≥ 5 events/hour) without CKD.
- CKD was defined as estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² using the MDRD equation.
- Serum cystatin C levels were measured, and associations with clinical factors were analyzed.
Main Results:
- Serum cystatin C correlated with age, BMI, AHI, C-reactive protein, and brachial-ankle pulse wave velocity.
- Severe OSA (AHI ≥ 30 events/hour) was independently associated with the highest quartiles of serum cystatin C (≥0.88 mg/L).
- This association remained significant after adjusting for age, BMI, hypertension, and diabetes mellitus.
Conclusions:
- Severe OSA independently increases serum cystatin C levels in patients without CKD.
- Elevated cystatin C in severe OSA patients may reflect subclinical renal dysfunction.
- Cystatin C could serve as a biomarker for both renal and cardiovascular risks associated with OSA.
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