Albuminuria and disease outcome measures in patients with COPD

Abstract

<bold>Background:</bold> Endothelial dysfunction (ED) plays a major role in pathogenesis of COPD. Albuminuria is a biomarker of generalized ED. Data on prevalence of albuminuria in COPD patients and its association with disease outcome measures are limited. <bold>Objective:</bold> To investigate the relationship between albuminuria, as a biomarker of ED, and disease outcome measures in COPD patients. <bold>Methods:</bold> 60 COPD patients and 40 non-COPD smokers were enrolled in this cross-sectional study. All participants were assessed for anthropometric parameters, oxygen saturation (SpO₂), spirometry, 6-minute walk test, flow-mediated dilation (FMD) of the brachial artery, routine laboratory measurements, and urinary albumin-to-creatinine ratio (UACR). <bold>Results:</bold> Patients with COPD had higher levels of UACR (mg/g) and more prevalence of albuminuria than non-COPD smokers. COPD patients with albuminuria had higher BMI, more frequent exacerbations, more mixed spirometric pattern, lower SpO₂, lower FMD, and higher fasting plasma glucose than patients without albuminuria. UACR in COPD patients was associated negatively with FMD and SpO₂ and positively with number of comorbidities and fasting plasma glucose. The main predictors of albuminuria in COPD patients were high BMI, low SpO₂, and high fasting plasma glucose. The only independent predictor of albuminuria was the presence of low SpO₂. <bold>Conclusion:</bold> Albuminuria is more prevalent in patients with stable COPD than in non-COPD smokers. Albuminuria in COPD patients is strongly associated with low SpO₂ independent of other risk factors. Given the negative association with FMD, the gold standard measure of ED, measurement of UACR should be routinely utilized for assessing ED in COPD patients, especially those with low SpO₂.