Albuminuria as a Risk Factor for Anemia in Chronic Kidney Disease: Result from the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD)

Abstract

Background: Anemia is a common complication among patients with chronic kidney disease (CKD), and it is associated with unfavorable clinical outcomes in patients with CKD independent of the estimated glomerular filtration rate (eGFR). We assessed the association of the urinary albumin-to-creatinine ratio (ACR) and eGFR with anemia in CKD patients.

Methods: We conducted a cross-sectional study using baseline data from the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease (KNOW-CKD). Multiple regression analysis was performed to identify the independent association of albuminuria with anemia. Furthermore, odds ratios for anemia were calculated by cross-categorization of ACR and eGFR.

Results: Among 1,456 patients, the mean age was 53.5 ± 12.4 years, and the mean eGFR and ACR were 51.9 ± 30.5 mL/min per 1.73 m2 and 853.2 ± 1,330.3 mg/g, respectively. Anemia was present in 644 patients (40.5%). Multivariate analysis showed that the odds ratio of anemia increased according to ACR levels, after adjusting for age, sex, eGFR, body mass index, pulse pressure, cause of CKD, use of erythropoiesis stimulating agents, serum calcium and ferritin (ACR < 30 mg/g as a reference group; 30-299 mg/g, adjusted odds ratio (OR) = 1.43, 95% confidence interval (CI) = 0.88-2.33; ≥300 mg/g, adjusted OR = 1.86, 95% CI = 1.12-3.10). In addition, graded associations were observed in cross-categorized groups of a higher ACR and eGFR compared to the reference group with an ACR <30 mg/g and eGFR ≥60 mL/min per 1.73 m2.

Conclusion: The present study demonstrated that albuminuria was a significant risk factor for anemia in CKD patients independent of the eGFR.

Trial registration: ClinicalTrials.gov NCT01630486.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1. Correlation of hemoglobin levels with albuminuria.

Hemoglobin levels are inversely related with Ln ACR levels (r = -0.281, P Abbreviation: ACR, albumin-to-creatinine ratio; Ln ACR, log-transformed albumin-to-creatinine ratio

Fig 2. The risk of anemia in relation to the ACR and eGFR.

By using generalized additive models, the risk (solid line) and 95% confidence intervals (dashed line) of anemia in relation to the (A) ACR and (B) eGFR is estimated. Abbreviations: ACR, albumin-to-creatinine ratio; eGFR, estimated glomerular filtration rate.