Renal function and sleep-disordered breathing in older men

Background. Sleep-disordered breathing (SDB) is common in severe chronic kidney disease (CKD) and may contribute to morbidity and mortality in this population. However, the association between mild to moderate CKD and likelihood of SDB is uncertain. Methods. We studied 2696 men >= 65 years (mean 73.0 +/- 5.5) enrolled in the Outcomes of Sleep Disorders in Older Men (MrOS Sleep) study who had serum creatinine (SCr) measured 3.4 years prior to overnight polysomnography (PSG). CKD was expressed as quartiles of estimated glomerular filtration rate (eGFR) using the four-variable Modification of Diet in Renal Disease (MDRD) formula. SDB was assessed using the respiratory disturbance index (RDI) with >= 4% oxygen desaturation. Results. Mean SCr was 0.99 +/- 0.20 mg/dl; 14.8% had eGFR < 60 ml/min/1.73 m(2). Median RDI was 7.4 events/hour (inter-quartile range 2.6-15.8). Lower eGFR was not associated with higher mean RDI in the unadjusted model (P for trend = 0.180). There was evidence of an interaction between eGFR and age for the prediction of RDI; an association between lower eGFR and higher RDI was evident only among men <= 72 (median) years. Among this age group, however, the association was not statistically significant after further adjustment for body mass index (BMI) (P for trend = 0.278). Conclusions. In this cohort of older community-dwelling men, reduced renal function was not associated with greater evidence of SDB, except among younger old men. However, this association was largely explained by higher BMI at lower eGFR. Further prospective study in younger populations is needed to clarify our findings.