Prevalence of chronic renal failure in COPD patients

COPD is a leading cause of death worldwide. It is associated with a large number of comorbidities. The current study included 300 COPD patients aged 65.28 ± 6.32 years, 148 of them (49.3%) were females and the rest were males and 300 control age and gender matched patients with diseases other than COPD; aged 64.70 ± 7.12 years, 138 of them (46%) were males and the rest were females. They were enrolled in the study during their follow up visits to the outpatient clinic of the Chest Department, Menoufiya University Hospitals from August 2009 to August 2012. The GFR was estimated and patients were categorized according to their renal function as having normal renal function (GFR ⩾ 60 mL/min/1.73 m2), concealed CRF (normal serum creatinine and GFR < 60 mL/min/1.73 m2), or overt CRF (increased serum creatinine and GFR < 60 mL/min/1.73 m2). In the COPD group; the mean BUN value was 22.86 ± 13.63, the mean serum creatinine concentration was 1.29 ± 0.67 mg/dL and the mean estimated GFR was 75.20 ± 35.78 mL/min/1.73 m2. In the control group; the mean BUN value was 14.04 ± 9.61, the mean serum creatinine concentration was 0.85 ± 0.34 mg/dL and the mean estimated GFR was 92.04 ± 25.54 mL/min/1.73 m2 (P < 0.01 for all in comparison with the COPD group). The prevalence of normal renal function, concealed CRF, and overt CRF in COPD group of patients was 54%, 26% and 20%, respectively. The corresponding figures in the control group were 78%, 10%, and 12%, respectively (COPD vs control group: P < 0.001). The overall prevalence of CRF (GFR < 60 mL/min/1.73 m2) was 46% in the study group and 22% in the control group (P < 0.001). COPD was significantly associated with both concealed and overt CRF. Age and hypoalbuminemia were significantly associated with overt CRF while the number of comorbidities was significantly associated with concealed CRF. CRF may be an important COPD comorbidity and should be screened for not only by serum creatinine level but also by the estimated GFR.