RESUMEN
Background: Obstructive sleep apnea syndrome (OSAS) is an independent risk factor for cardiovascular morbidity and mortality, and it has a detrimental effect on renal function. Obesity is the major risk factor for OSAS, and represents a risk factor for chronic kidney disease. Continuous positive airway pressure (CPAP) is the suggested therapy for moderate-to-severe OSAS. We designed this study to evaluate the effect of CPAP on estimated glomerular filtration rate (e-GFR) in a cohort of obese patients with moderate-to-severe OSAS and normal renal function. Methods: We enrolled 198 obese subjects, divided into two groups (OSAS+ and OSAS-), on the basis of cardiorespiratory monitoring; mild OSAS patients (n = 33) were excluded from the study, thus the analyses were conducted on 165 patients. Comparisons between groups were made by Student t-test or χ2 test as appropriate. Linear regression analyses were used to assess the relationship between baseline e-GFR and different covariates and, in the OSAS+ group, between Δe-GFR and different covariates. A multivariate regression analysis was performed to determinate the independent predictor of the Δe-GFR. Results: OSAS+ subjects showed significantly increased values of systolic blood pressure, HOMA, pulse wave velocity, high-sensitivity C reactive protein and uric acid compared with OSAS- group. OSAS+ group showed significantly lower values of e-GFR and increased values of microalbuminuria. At linear regression analysis e-GFR resulted significantly and inversely related to AHI in the whole study population and in the two groups. After 6 months of CPAP therapy, OSAS+ subjects showed an improvement in respiratory parameters, as well as a significant increase in e-GFR values (104.2 + 19.0 vs. 84.0 + 13.1 ml/min/1.73 m2, P < 0.0001). At multiple regression analysis, Δ apnea/hypopnea index (AHIa) resulted the main independent predictor of Δe-GFR explaining 22% of its variation. Conclusions: Obese OSAS patients show significantly lower values of e-GFR, even if in the normal range, compared with obese non-OSAS subjects. After 6 months of CPAP, e-GFR significantly improved (+20 ml/min/1.73 m2) and ΔAHIa resulted the most important independent predictor of Δe-GFR.
RESUMEN
OBJECTIVE: Subjects who are normal glucose tolerant (NGT) are considered at low risk, even if a plasma glucose value ≥155 mg/dL for the 1-h postload plasma glucose during an oral glucose tolerance test (OGTT) is able to identify NGT subjects at high risk for type 2 diabetes and subclinical organ damage. Hyperuricemia is associated with several risk factors for cardiovascular diseases such as hypertension, insulin resistance, and diabetes. However, it is unknown whether uric acid (UA) is able to affect 1-h postload plasma glucose in hypertensive NGT subjects. RESEARCH DESIGN AND METHODS: From a cohort of â¼1,200 uncomplicated hypertensive outpatients who underwent OGTT, we selected 955 subjects (548 men and 407 women) aged 45.6 ± 10.1 years. Laboratory evaluations were performed, and estimated glomerular filtration rate was assessed by using the new equation proposed by investigators in the Chronic Kidney Disease Epidemiology Collaboration. RESULTS: Considering different stepwise multivariate linear regression models, UA was the major predictor of 1-h postload glucose in the entire population, with NGT ≥155 subjects, impaired glucose tolerant, and type 2 diabetic patients accounting for 26.0% (P < 0.0001), 25.3% (P < 0.0001), 13.5% (P < 0.0001), and 13.5% (P = 0.003) of its variation in the respective models. CONCLUSIONS: We documented that in hypertensive NGT ≥155 subjects, UA is strongly associated with 1-h postload glucose, similarly to what is observed in impaired glucose tolerant and diabetic patients.
