Anemia as a risk factor for all-cause mortality: obscure synergic effect of chronic kidney disease

Abstract

Background: Anemia is common in chronic kidney disease (CKD) and may be associated with mortality in CKD patients. However, few studies have examined this relationship in Asian populations.

Methods: A total of 62,931 Japanese people (age 64.0 ± 8.0 years; men 38.5%) were followed up from 2008 to 2012. Participants were divided into six groups in accordance with their estimated glomerular filtration rate (eGFR) (<45, 45-59, ≥60 mL/min/1.73 m²) and by hemoglobin levels (13.0 g/dL for men; 12.0 g/dL for women). Hazard ratio and confidence interval (CI) for mortality with a combination of eGFR and anemia were calculated. After matching using propensity score (PS) for anemia, survival analysis between anemic and non-anemic people, independent from some variables, including eGFR, was performed.

Results: A total of 828 (1.3%) participants died (non-anemic vs. anemic, 1.2 vs. 2.3%, p < 0.01). Multivariable Cox analysis showed that, independent of eGFR levels, anemic people had significantly higher mortality. Anemic people were found to have significantly poorer survival than non-anemic people as per a log-rank test (p < 0.01) for the PS-matching cohort. Further stratified logistic analysis using PS in the overall cohort odds ratio (95% CI) showed 2.25 (1.89-2.67) with p < 0.01.

Conclusion: The results of the present study showed that anemia was an independent risk factor of all-cause mortality.

Keywords: All-cause mortality; Anemia; Chronic kidney disease; Propensity score.