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EVALUATION OF RENAL FUNCTION IN A COHORT OF PATIENTS AFFECTED BY
OBSTRUCTIVE SLEEP APNEA
Pozzi P 1 , Marelli S 1 , Tripepi G 2 , Zoccali C 2 , Ferini Strambi L 1
1 Sleep Medicine Center, San Raffaele Turro Scientific Institute, Milano
2 CNR-IBIM, Reggio Calabria
Introduction: Obstructive sleep apnea (OSA) has been recently linked to mild chronic
kidney disease (CKD); furthermore, indexes of OSA severity, namely apnea-hypopnea
index (AHI), have been related to microalbuminuria, a potent predictor of adverse
cardiovascular events. We therefore sought to determine the renal function of a cohort of
non-CKD patients admitted to our Sleep Medicine Unit for OSA.
Materials and Methods: 374 subjects (M=310) underwent a cardiorespiratory
polysomnography and a blood samples collection for creatinine. Oronasal airflow was
measured with a thermistor and/or a pressure transducer, respiratory efforts were
monitored by either thoraco-abdominal strain gauges or uncalibrated inductance
plethysmography, oxyhaemoglobin saturation by pulse oximetry. Respiratory events were
scored manually according to the American Academy of Sleep Society’s rules. Estimation
of glomerular filtration rate (GFR) was calculated trough the Modification of Diet in Renal
Disease (MDRD) Study Equation. Descriptive statistic (mean + SD), analysis of variance
(ANOVA), Pearson’s correlations as well as linear regressions with GFR as dependent
variable were performed. A p value of less than 0.05 was considered to be significant.
Results: Patients were 53,1 + 12 years old, with a mean BMI of 32.4 + 6.6. They were
normotensive (SBP=132 + 13.2 mmhg; DBP=82.3 + 9.3 mmhg) and euglycemic (fasting
glycemia=95.7 + 20.5 mg/dL). Creatinine was 0.88 + 0.18 mg/dL, with an estimated GFR
of 95.1 + 19 mL/min/1.73 m 2 . The population was suffering from severe OSA (AHI=45.8 +
19.7 events/h; min spO2=72.2 + 10.9% ; T