Background: Chronic obstructive pulmonary disease (COPD) is recognized as a source of systemic inflammation and is associated with the development of cardiovascular disease. However, little is known about the association between COPD and chronic kidney disease (CKD). Therefore, we investigated the relationship between COPD and CKD and the association between COPD and mortality in patients with CKD.
Methods: We conducted a cohort study of 3358 vascular surgery patients between 1990 and 2006. CKD was defined according to the Modification of Diet in Renal Disease equation as an estimated glomerular filtration rate (GFR) <60 mL/min/1.73 m(2). In addition, the patients were divided into three categories based on the baseline estimated GFR: > or =90 mL/min/1.73 m(2); 60-89 mL/min/1.73 m(2) and <60 mL/min/1.73 m(2). Multivariable logistic regression analysis was used to evaluate the independent association between prevalent COPD and CKD.
Results: The prevalence of COPD was inversely related to kidney function. COPD was present in 47, 38 and 32% of patients with an estimated GFR <60, 60-89 and > or =90 mL/min/1.73 m(2), respectively. COPD was independently associated with CKD (OR 1.22; 95% CI 1.03-1.44; P = 0.03). This association was strongest in patients with moderate COPD (OR 1.33; 95% CI 1.07-1.65; P = 0.01). Both moderate and severe COPD were associated with increased long-term mortality in patients with CKD (HR 1.27; 95% CI 1.03-1.56; P = 0.03 and HR 1.61; 95% CI 1.10-2.35; P = 0.01, respectively), compared to patients without COPD.
Conclusions: Our findings indicate that COPD is moderately associated with CKD in a large cohort of vascular surgery patients. In addition, moderate and severe COPD are related to increased long-term mortality in patients with CKD.