Exploration of anaemia as a progression factor in African Americans with cardiovascular disease

Estimating the causal effect of transient anemia status on renal and cardiovascular outcomes in community-dwelling patients in Japan at the beginning of impaired renal function using marginal structural modeling

Background

Anemia status may be transient. Causal associations between changes in anemia status over time and adverse outcome development are not well characterized in community-dwelling subjects at the beginning of impaired kidney function.

Methods

This retrospective cohort study used annual health checkup and medical and pharmacy claims data from the JMDC between January 2005 and June 2019. Community-dwelling subjects in Japan with a pre-index estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m² followed by a subsequent eGFR < 60 mL/min/1.73 m² (index) were included. The composite renal outcome was ≥ 30% eGFR reduction over 3 years from baseline, serum creatinine doubling, progression to chronic dialysis, kidney transplantation, or eGFR < 15 mL/min/1.73 m². The composite cardiovascular outcome was fatal and non-fatal unstable angina, myocardial infarction, heart failure, or cerebrovascular event. Time-dependent anemia risk was evaluated using Breslow’s estimator and marginal structural Cox models (MSM).

Results

In 32,870 included subjects, 1,396 had anemia at baseline. Adverse outcome incidence was higher in the baseline anemic group, but absolute differences in renal and cardiovascular outcomes between groups were diminished after adjusting for baseline characteristics. In MSM, time-dependent anemia status was associated with higher risk of renal (hazard ratio [95% confidence interval]; 2.6 [1.7–3.8]) and cardiovascular (1.6 [1.2–2.2]) outcomes and mortality (2.8 [1.8–4.3]). Absolute differences in survival probabilities were retained over time but were clinically marginal (1.1–2.7% over 6 years).

Conclusions

Even in subjects at the very early stage of impaired kidney function, early detection and treatment of anemia may help reduce the development of negative sequelae.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10157-021-02137-1.

Anemia and Incident End-Stage Kidney Disease

Background

Chronic kidney disease (CKD) progression can be a cause and potentially a consequence of anemia. Previous studies suggesting that anemia is associated with CKD progression have not utilized methodologic approaches to address time-dependent confounding.

Methods

We evaluated the association of anemia (defined using World Health Organization criteria of hemoglobin <12 g/dL in women and <13 g/dL in men) with incident ESRD and all-cause death in individuals with CKD using data from the Chronic Renal Insufficiency Cohort Study. Marginal structural models were used to account for time-dependent confounding.

Results

Among 3919 participants, 1859 (47.4%) had anemia at baseline. Over median follow up of 7.8 years, we observed 1,010 ESRD events and 994 deaths. In multivariable analyses, individuals with anemia had higher risk for ESRD compared to those without (HR 1.62, 95% CI 1.24-2.11). In stratified analyses, the increased risk for incident ESRD with anemia was observed in males (HR 2.15, 95% CI: 1.53-3.02) but not females (HR 1.20, 95% CI 0.82-1.78. The association between anemia and ESRD was significant among all racial/ethnic groups except non-Hispanic blacks (non-Hispanic white, HR 2.16, 95% CI 1.53-3.06; Hispanic, HR 1.92, 1.04-3.51; others, HR 2.94; 95% CI 1.16-7.44; non-Hispanic black, HR 1.39; 95% CI 0.95-2.02). There was no association between anemia and all-cause death.

Conclusions

In this cohort, anemia was independently associated with increased risk for incident ESRD. Future work is needed to evaluate the mechanisms by which anemia leads to CKD progression as well as the impact of novel therapeutic agents to treat anemia.