Association of mild anemia with hospitalization and mortality in the elderly: the Health and Anemia population-based study

Abstract

Background: Mild anemia is a frequent laboratory finding in the elderly usually disregarded in everyday practice as an innocent bystander. The aim of the present population-based study was to prospectively investigate the association of mild grade anemia with hospitalization and mortality.

Design and methods: A prospective population-based study of all 65 to 84 year old residents in Biella, Italy was performed between 2003 and 2007. Data from a total of 7,536 elderly with blood tests were available to estimate mortality; full health information available to evaluate health-related outcomes was available for 4,501 of these elderly subjects. Mild grade anemia was defined as a hemoglobin concentration between 10.0 and 11.9 g/dL in women and between 10.0 and 12.9 g/dL in men.

Results: The risk of hospitalization in the 3 years following recruitment was higher among the mildly anemic elderly subjects than among subjects who were not anemic (adjusted hazard ratio: 1.32; 95% confidence interval: 1.09-1.60). Mortality risk in the following 3.5 years was also higher among the mildly anemic elderly (adjusted hazard ratio: 1.86; 95% confidence interval: 1.34-2.53). Similar results were found when slightly elevating the lower limit of normal hemoglobin concentration to 12.2 g/dL in women and to 13.2 g/dL in men. The risk of mortality was significantly increased in mild anemia of chronic disease but not in that due to beta-thalassemia minor.

Conclusions: After controlling for many potential confounders, mild grade anemia was found to be prospectively associated with clinically relevant outcomes such as increased risk of hospitalization and all-cause mortality. Whether raising hemoglobin concentrations can reduce the risks associated with mild anemia should be tested in controlled clinical trials.

Figure 1.

Time to first hospitalization by sex and mild anemia status in the Health and Anemia population-based study (2003–2007). Kaplan-Meier curves for individuals aged 65–84 years (n = 4,470) over 3 years after blood sampling. Mild anemia was defined as a hemoglobin concentration between 10.0 and 11.9 g/dL in women and between 10.0 and 12.9 g/dL in men.

Figure 2.

(A) Age-adjusted hazard ratios of death (95% CI) by hemoglobin concentration in women aged 65–84 years (n = 4,561) from 60 days to 3.5 years after blood sampling in the Health and Anemia population-based study (2003–2007). (B) Age-adjusted hazard ratios of death (95% CI) by hemoglobin concentration in men aged 65–84 years (n = 2,975) from 60 days to 3.5 years after blood sampling in the Health and Anemia population-based study (2003–2007).

Figure 3.

Time to death by sex and mild anemia status in the Health and Anemia population-based study (2003–2007). Kaplan-Meier curves for individuals aged 65–84 years (n = 7,406) from 60 days to 3.5 years after blood sampling. Mild anemia was defined as a hemoglobin concentration between 10.0 and 11.9 g/dL in women and between 10.0 and 12.9 g/dL in men.