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Anaemia and mortality in older people

Admission with heart failure [1]
Results
Anaemia predicts mortality in heart failure [2]
Results
Myocardial infarction [3]
Results
Comment

Bandolier 137 examined a systematic review of the prevalence of anaemia in older people, and noted that prevalence increased with age, and was rather high. What was not clear was any relationship between anaemia and any other consequences. Anaemia was associated with higher rates of Alzheimer's disease, poorer health, more hospital admission, and greater mortality, though none of the studies reporting this was large. A further search has found more information from three studies relating anaemia, heart failure, kidney failure, and mortality.

Admission with heart failure [1]

The population was all Medicare patients admitted in a US state over six months with a primary diagnosis of heart failure. Retrospectively information from patient records was abstracted, with follow up over more than two years.

Results

After excluding patients with frank renal failure, who died before discharge, or who were lost to follow up, 665 such patients were eligible. Their average age was 76 years, with a range of 29 to 100 years. Multiple conditions were recorded including hypertension, diabetes, coronary artery disease, myocardial infarction, stroke, and angina. With decreasing haematocrit, the proportion with chronic renal disease, or who died within the first year, or 2.5-year mortality, increased significantly (Figure 1).



Figure 1: Chronic renal disease, and one year and 2.5 year mortality with haematocrit in older patients with heart failure





Anaemia predicts mortality in heart failure [2]

Baseline and follow up data from a randomised trial of amlodipine versus placebo in 1,130 patients with severe heart failure were used. Average age was 65 years. Follow up was over 15 months, and there were 407 deaths, predominantly cardiac deaths. Patients were divided into quintiles according to their baseline haematocrit. The lowest quintile had a haematocrit of <38% and haemoglobin of 116 g/L.

Results

In the lowest quintile total mortality was 41%, compared with 25-28% across other quintiles. It was significantly higher, with a hazard ratio of 1.5 (1.1 to 2.1) adjusting for a range of factors. In this lowest quintile each 1% fall in haematocrit was associated with an 11% higher risk of death.

There was a strong effect of haematocrit across all quintiles for pump failure death (Figure 2), with significant increased risk in all four lower quintiles compared with the highest quintile. There was no effect on sudden or other deaths.



Figure 2: Pump failure deaths over 15 months and baseline haematocrit in patients with severe heart failure





Myocardial infarction [3]

Another retrospective cohort study randomly selected 15% of patients discharged from hospital with the primary diagnosis of acute myocardial infarction in a single US state. Follow up was over 2.5 years.

Results

After obvious exclusions, information from 559 patients was available. The average age was 74 years, ranging from 32 to 97 years. As haematocrit on admission fell from 40% to under 30%, the prevalence of chronic renal disease rose from 48% to 80%, and one-year mortality from 19% to 42%. Low creatinine clearance and low haematocrit were independent risk factors for risk of death within one year. The risk was very high with both factors (Figure 3).



Figure 3: One-year mortality after myocardial infarction according to haematocrit and creatinine clearance





Comment

Chronic anaemia is known to have effects on the heart, increasing heart rate and how much the heart has to work. That's obvious, because if the body demands a certain amount of oxygen, but the oxygen carrying capacity of the blood is reduced, more blood has to be pumped in a given time. The heart is stressed.

The relationship between renal failure and anaemia is complex, especially as regards causation. Renal failure may contribute to anaemia, but anaemia may also contribute to renal impairment. Both anaemia and renal impairment may be also be caused by some other factor that is itself a cause of increased mortality.

What we do not know is whether treating the anaemia does any good. So far there is little to help, but the question of transfusion for anaemia after a heart attack is tiger territory, with studies pointing to different conclusions. What we are left with for the moment is a few stark facts. Anaemia is not a good thing in older people with heart failure or heart attack. Nor is renal insufficiency. Having both is very bad.

References:

  1. WM McLennan et al. Anemia and renal insufficiency are independent risk factors for death among patients with congestive heart failure admitted to community hospitals: a population-based study. Journal of the American Society of Nephrology 2002 13: 1928-1936.
  2. D Mozaffarian et al. Anemia predicts mortality in severe heart failure. Journal of the American College of Cardiology 2003 41: 1933-1939.
  3. RD Langston et al. Renal insufficiency and anemia are independent risk factors for death among people with acute myocardial infarction. Kidney International 2003 64: 1398-1405.

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