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

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.

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.

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.

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