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Race, anaemia, and mortality

Study
Results
Comment

Anaemia and mortality has been looked at before by Bandolier (138, 146). We know that anaemia is more common in older people, and perhaps more in women than men, and there have been indications of some racial differences as well. A new study [1] not only confirms some of the racial differences in anaemia prevalence, but also indicates that the consequences of anaemia may differ according to race.

Study

The study included people aged 70-79 years in Memphis and Philadelphia who were living in the community, could walk a quarter of a mile without difficulty, climb stairs without resting, and were performing basic activities of daily living. Exclusions included use of a walking device, treatments for cancer , or being in a clinical trial. In 2000 baseline haemoglobin values were assessed in 2,601 people, and anaemia assessed using the WHO criteria of <120 g/L for women and <130 g/L for men. Race was self-reported.

Mortality was the primary outcome over the period to August 2005. A secondary outcome was mobility disability.

Results

The population was about 50% women and 40% black, and the mean age was 75 years. Compared with white people, black people had a higher BMI, had better renal function, and were less likely to have cancer, but more likely to have coronary heart disease, diabetes, ulcers, and hypertension.

For women and men, mean haemoglobin concentrations were about 10 g/L lower for blacks than whites. More black people had lower haemoglobin levels than white people (Figures 1 and 2). WHO defined anaemia was found in 21% of black women compared with 7% of white women, and 26% of black and 14% of white men.



Figure 1: Distribution of haemoglobin concentrations in black and white women







Figure 2: Distribution of haemoglobin concentrations in black and white men





Mortality was significantly higher among black women and men than white (Figure 3). Mortality was not affected by the presence of anaemia in black women and men, but was significantly higher in white women and men with WHO-defined anaemia. An eGFR below 60 mL/min/1.73 sq m was associated with higher anaemia mortality in blacks and whites.



Figure 3: Mortality (per 1,000 patient years) according to anaemia status, sex, and race





Developing mobility disability was also significantly associated with anaemia in white women and men, but not in blacks.

Comment

When considering anaemia in older people, we may need to take more account of race. This study looked only at black and white people, as they defined themselves. There was no category for Asian or other ethnic origins.

For older black people, we may need to revisit the WHO criteria and come up with race-specific criteria. It certainly appears that black men and women function reasonably well at lower levels of haemoglobin and better than their white counterparts.

We also need to be careful about mortality rates. While there is a significantly greater mortality with anaemia, this appears to have more to do with lower rates of death in white women and men who were not anaemic than higher death rates in anaemic black women and men. The difference in mortality being anaemic and non-anaemic seems to be bigger in white women and men than in black women and men.

References:

  1. KV Patel et al. Racial variations in the relationship of anemia with mortality and mobility disability among older adults. Blood 2007 DOI 10.1182/blood-2006-10-055384

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