Is Renal Impairment an Anticipated COPD Comorbidity?

BACKGROUND: Many studies have investigated COPD-linked comorbidities and their influence on associated outcomes, but the extent to which COPD is related to chronic renal failure is undetermined. The objective of this work was to assess the prevalence of chronic renal failure (overt or concealed) in a cohort with COPD compared with that of a control group, and to investigate the relationships of the clinical and functional data with the subjects' renal conditions. METHODS: The study was performed with 136 subjects with COPD and 104 control subjects. The subjects with COPD were divided into 2 groups according to a combined assessment. The COPD and control groups were compared in terms of clinical factors, renal function, estimated glomerular filtration rate, and spirometry data. The prevalence of the renal status types was examined in all groups, and the correlations of serum creatinine and estimated glomerular filtration rate with all of the clinical and spirometry data were examined. RESULTS: There were significant differences between both COPD groups and the controls regarding estimated glomerular filtration rate. Significantly worse renal function was observed in the COPD group, which also exhibited a greater percentage of subjects with concealed chronic renal failure. Additionally, there were significant differences in renal status among the 3 groups; the percentage of subjects with concealed chronic renal failure was significantly greater in group 2 than in both group 1 and the control group. Additionally, the percentages of subjects with concealed chronic renal failure were greater than those with overt chronic renal failure in the 3 groups. There were significant correlations of serum creatinine with COPD assessment test, exacerbations and hospitalizations, percent-of-predicted FVC, percent-of-predicted FEV 1 /FVC, percent-of-predicted maximum mid-expiratory flow, and percent-of-predicted peak expiratory flow. Moreover, there were significant correlations between estimated glomerular filtration rate and all of the clinical and spirometry data. CONCLUSIONS: Chronic renal failure should not be ignored or underestimated in patients with COPD because it frequently cannot be recognized based on serum creatinine because decreases in estimated glomerular filtration rate are more prevalent.