Microalbuminuria and Hypoxemia in Patients with Chronic Obstructive Pulmonary Disease

Abstract

Rationale: Microalbuminuria (MAB), a marker of endovascular dysfunction, is a predictor of cardiovascular events and all-cause mortality in the general population. There is evidence of vascular dysfunction in patients with chronic obstructive pulmonary disease (COPD). Objectives: To assess the prevalence and relationship of MAB with clinical and physiological parameters in stable patients with COPD. Methods: We measured urinary albumin rate (urinary albumin to creatinineratio:UACR),smokinghistory,arterialbloodpressure,gas exchange, body massindex, lung function, BODE index (body mass index, airflow obstruction, dyspnea, exercise performance), and comorbidityindexin129patientswithstableCOPDand51smokers withnormalspirometrywithoutknowncardiovasculardisease.MAB levels were compared between groups. A multivariate analysis was performed to determine the best determinants of MAB levels. Measurements and Main Results: MAB was higher in patients with COPDthanin control smokers (8 [5th295th percentile (P5–95), 2.9113] vs. 4.2 [P5–95, 1.8–22.7] mg/g, P , 0.001]). The difference remained significant even after using the standard pathologic threshold (MAB, 30–299 mg/g in women and 20–299 mg/g in men; 24% in patients with COPD vs. 6% in control smokers; P 5 0.005). In patients with COPD, there was a negative correlation between PaO2 and MAB (r 520.40, P , 0.001). Using multivariate analysis, MABwasonlyassociatedwiththePaO2 (relativerisk,0.934; 95% confidence interval, 0.880–0.992; P , 0.001) and with the systolic arterial blood pressure (relative risk, 1.034; 95% confidence interval, 1.011–1.057; P 5 0.003). Conclusions:MABisfrequentinpatientswithCOPDandisassociated with hypoxemia independent of other cardiovascular risk factors. Further studies are necessary to investigate whether MAB could be anearly simplebiomarkerofcardiovascular compromise in patients with COPD.