Anemia in centenarians: prevalence and association with kidney function

Modification Effects of Albuminuria on the Association Between Kidney Function and Development of Anemia in Diabetes

CONTEXT

Previous studies failed to adjust for estimated glomerular filtration rate (eGFR) in evaluating the association between albuminuria and anemia development, and we aimed to investigate whether albuminuria independently affects anemia development.

METHODS

We conducted a retrospective cohort study and retrospectively identified adults with diabetes from a Japanese nationwide clinical database (JMDC, Tokyo, Japan). To assess the modification effects of albuminuria on the association between eGFR and anemia development, we estimated prevalence of anemia, defined as hemoglobin < 13 g/dL in men and < 12 g/dL in women, using a modified Poisson regression and marginal standardization form of predictive margins, stratified by albuminuria severity after adjusting for eGFR. Hence, we revealed at which eGFR level this modification effect appeared and the extent to which this modification effect increased the prevalence of anemia.

RESULTS

We identified 327 999 data points from 48 056 individuals [normoalbuminuria: 186 472 (56.9%), microalbuminuria: 107 170 (32.7%), and macroalbuminuria: 34 357 (10.5%)]. As eGFR declined, anemia prevalence increased. Albuminuria severity modified this association induced by decreased eGFR among individuals with eGFR <30 mL/min/1.73 m2 after adjusting for multivariable factors, including age, sex, comorbidities, and medication use. Compared with the normoalbuminuric group, the macroalbuminuric group had a 5% to 20% higher anemia prevalence among individuals with eGFR of <30 mL/min/1.73 m2.

CONCLUSION

We revealed that the severity of albuminuria modified the association between eGFR and anemia development among individuals with eGFR <30 mL/min/1.73 m2, highlighting the modification effect of albuminuria on the association between kidney function and anemia development in diabetes.

Differential Iron Requirements for Osteoblast and Adipocyte Differentiation

Bone marrow mesenchymal progenitor cells are precursors for various cell types including osteoblasts, adipocytes, and chondrocytes. The external environment and signals act to direct the pathway of differentiation. Importantly, situations such as aging and chronic kidney disease display alterations in the balance of osteoblast and adipocyte differentiation, adversely affecting bone integrity. Iron deficiency, which can often occur during aging and chronic kidney disease, is associated with reduced bone density. The purpose of this study was to assess the effects of iron deficiency on the capacity of progenitor cell differentiation pathways. Mouse and human progenitor cells, differentiated under standard osteoblast and adipocyte protocols in the presence of the iron chelator deferoxamine (DFO), were used. Under osteogenic conditions, 5μM DFO significantly impaired expression of critical osteoblast genes, including osteocalcin, type 1 collagen, and dentin matrix protein 1. This led to a reduction in alkaline phosphatase activity and impaired mineralization. Despite prolonged exposure to chronic iron deficiency, cells retained viability as well as normal hypoxic responses with significant increases in transferrin receptor and protein accumulation of hypoxia inducible factor 1α. Similar concentrations of DFO were used when cells were maintained in adipogenic conditions. In contrast to osteoblast differentiation, DFO modestly suppressed adipocyte gene expression of peroxisome-proliferating activated receptor gamma, lipoprotein lipase, and adiponectin at earlier time points with normalization at later stages. Lipid accumulation was also similar in all conditions. These data suggest the critical importance of iron in osteoblast differentiation, and as long as the external stimuli are present, iron deficiency does not impede adipogenesis. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Associations Between Anemia, Cognitive Impairment, and All-Cause Mortality in Oldest-Old Adults: A Prospective Population-Based Cohort Study

Objective: To evaluate the combined effects of anemia and cognitive function on the risk of all-cause mortality in oldest-old individuals. Design: Prospective population-based cohort study. Setting and Participants: We included 1,212 oldest-old individuals (men, 416; mean age, 93.3 years). Methods: Blood tests, physical examinations, and health questionnaire surveys were conducted in 2012 were used for baseline data. Mortality was assessed in the subsequent 2014 and 2018 survey waves. Cox proportional hazards models were used to evaluate anemia, cognitive impairment, and mortality risk. We used restricted cubic splines to analyze and visualize the association between hemoglobin (Hb) levels and mortality risk. Results: A total of 801 (66.1%) deaths were identified during the 6-year follow-up. We noted a significant association between anemia and mortality (hazard ratio [HR] 1.32, 95% confidence interval [CI] 1.14-1.54) after adjusting for confounding variables. We also observed a dose-response relationship between the severity of anemia and mortality (P < 0.001). In the restricted cubic spline models, Hb levels had a reverse J-shaped association with mortality risk (HR 0.88, 95% CI 0.84-0.93 per 10 g/L-increase in Hb levels below 130 g/L). The reverse J-shaped association persisted in individuals without cognitive impairment (HR 0.88, 95% CI 0.79-0.98 per 10 g/L-increase in Hb levels below 110 g/L). For people with cognitive impairment, Hb levels were inversely associated with mortality risk (HR 0.83, 95% CI 0.78-0.89 per 10 g/L-increase in Hb levels below 150 g/L). People with anemia and cognitive impairment had the highest risk of mortality (HR 2.60, 95% CI 2.06-3.27). Conclusion: Our results indicate that anemia is associated with an increased risk of mortality in oldest-old people. Cognitive impairment modifies the association between Hb levels and mortality.