Clinical significance of microalbuminuria and hypoxemia in patients with chronic obstructive pulmonary disease

Abstract

Background: Cardiovascular disease is a major cause of mortality in chronic obstructive pulmonary disease (COPD), particularly in patients with mild to moderate severity. Microalbuminuria (MAB) has a strong association with cardiovascular events and death, and it reflects generalized endothelial dysfunction. There is evidence of vascular dysfunction in patients with COPD. Objectives: (a) To study the prevalence of MAB in stable COPD patients. (b) To determine the relationship of MAB with clinical and physiological descriptors of COPD severity and cardiovascular risk factors. Materials and Methods: A cross-sectional study in 150 COPD patients over a period of 1 year. Lung function, 6-min walk distance, smoking history, arterial blood pressure (BP), BODE index, and arterial blood gases were measured. Screening for MAB was done by measuring urinary albumin-to-creatinine ratio in a random spot urine collection. Stepwise logistic regression was performed using MAB as the dependent variable. P < 0.05 was taken as statistically significant. Results: Forty-six patients (30.0%) had MAB. There was negative association between hypoxemia and MAB. Stepwise logistic regression analysis with MAB as the dependent variable showed smoking (odds ratio [OR]: 2.29; 95% confidence interval [CI]: 1.54-3.41), lower forced expiratory volume in 1 s % (OR: 1.04; 95% CI: 0.98-1.10), and PaO2 (OR: 0.68; 95% CI: 0.57-0.83) as independent predictors of MAB. Conclusions: MAB in severe COPD patients should be examined in regular periods for risk of cardiovascular morbidity or mortality.

Keywords

• 6-min walk distance
• BODE index
• chronic obstructive pulmonary disease
• forced expiratory volume in 1 s%
• hypercapnia
• hypoxemia
• microalbuminuria
• modified Medical Research Council
• pack-years