Microalbuminuria in Subjects With COPD: Relationship to the New Version of Global Initiative for Chronic Obstructive Lung Disease Staging.

BACKGROUND: Microalbuminuria, used as a marker of endothelial dysfunction, is a predictor of mortality for any reason and of cardiovascular events. Recent research on the management of COPD has focused more on comorbidities, including cardiovascular events. The objective of this study was to investigate the incidence of microalbuminuria and whether it is associated with physiological and clinical features in a subject group that was classified in line with the new version of the Global Initiative for Chronic Obstructive Lung Disease stages.

METHODS: The study included 105 stable subjects with mild to very severe COPD. The urinary albumin/creatinine ratio was calculated using a previously defined formula. The presence of microalbuminuria was accepted as a urinary albumin/creatinine ratio ≥20 in males and ≥30 in females.

RESULTS: Urinary albumin/creatinine ratios were significantly higher in subjects grouped as having more symptoms and high future risk than in those with fewer symptoms and low future risk. In addition, significant differences were observed when the subjects were grouped based on PaO2 (≤65 mm Hg vs >65 mm Hg), PaCO2 (≤41 mm Hg vs >41 mm Hg), arterial oxygen saturation (≤92% vs >92%), and median split C-reactive protein (≤4.6 mg/L vs >4.6 mg/L). Pearson correlation analysis revealed that the urinary albumin/creatinine ratio was significantly inversely correlated with percent-of-predicted FEV1 (r = -0.56, P = .001), percent-of-predicted SaO2 (r = -0.48, P = .001), and PaO2 (r = 0.60, P = .001). A positive correlation was also found between urinary albumin/creatinine ratio and COPD assessment test scores (r = 0.53, P = .001).

CONCLUSIONS: The results of this study indicate a strong relationship between microalbuminuria and cardiovascular events in subjects with COPD, particularly in subjects with more symptoms and high future risk. Therefore, microalbuminuria should be regularly monitored in this subgroup of subjects with COPD for risk of cardiovascular morbidity or mortality.