Renal function and sleep-disordered breathing in older men

Abstract

Background. Sleep-disordered breathing (SDB) is com- mon in severe chronic kidney disease (CKD) and may con- tribute to morbidity and mortality in this population. How- ever, 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 polysomnog- raphy (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 m2. 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 in- teraction 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,reducedrenalfunctionwasnotassociatedwithgreater evidence of SDB, except among younger old men. How- ever, this association was largely explained by higher BMI at lower eGFR. Further prospective study in younger pop- ulations is needed to clarify our findings.