Microalbuminuria and hypoxemia in patients with chronic obstructive pulmonary disease.
BACKGROUND
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).


OBJECTIVE
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 creatinine ratio: UACR), smoking history, arterial blood pressure, gas exchange, body mass index, lung function, BODE index (body mass index, airflow obstruction, dyspnea, exercise performance), and comorbidity index in 129 patients with stable COPD and 51 smokers with normal spirometry without known cardiovascular disease. MAB levels were compared between groups. A multivariate analysis was performed to determine the best determinants of MAB levels.


RESULTS
MAB was higher in patients with COPD than in control smokers (8 [5th-95th percentile (P₅₋₉₅), 2.9-113] 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 = 0.005). In patients with COPD, there was a negative correlation between Pa(O₂) and MAB (r = -0.40, P < 0.001). Using multivariate analysis, MAB was only associated with the Pa(O₂) (relative risk, 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 = 0.003).


CONCLUSIONS
MAB is frequent in patients with COPD and is associated with hypoxemia independent of other cardiovascular risk factors. Further studies are necessary to investigate whether MAB could be an early simple biomarker of cardiovascular compromise in patients with COPD.
Casanova
Ciro
C
Respiratory Research Unit, Pulmonary Department, Hospital Universitario La Candelaria, 38010 Santa Cruz de Tenerife, Spain. casanovaciro@gmail.com
de Torres
Juan P
JP
Navarro
Juan
J
Aguirre-Jaíme
Armando
A
Toledo
Pablo
P
Cordoba
Elizabeth
E
Baz
Rebeca
R
Celli
Bartolomé R
BR
D000368:Aged; D000419:Albuminuria / Q000453:epidemiology*; D015415:Biomarkers; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000517:prevention & control* / Q000652:urine; D016022:Case-Control Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology*; D008297:Male; D015999:Multivariate Analysis; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D018570:Risk Assessment; D012907:Smoking / Q000453:epidemiology; D013030:Spain / Q000453:epidemiology
D015415:Biomarkers