Prior reports have linked anemia with mortality, but “it remains unclear whether anemia is an independent cause of functional decline and increased mortality, or whether the strong association between anemia and these two states can be explained by comorbidity,” Wendy P. J. den Elzen and colleagues, from Leiden University Medical Center, the Netherlands, note in the July 27th online issue of CMAJ.
To investigate the independent effect of anemia on mortality in old age, the researchers analyzed data from 562 subjects who were 85 years of age and enrolled in the Leiden 85-plus Study, a population-based, prospective investigation. Various functional parameters were assessed at baseline and then every 5 years.
Nearly 27% of subjects had anemia at baseline and incident anemia developed in 24% of subjects during follow up, according to the report.
On initial analysis, anemia at baseline was associated with greater disability in activities of daily living, worse cognitive function, and more depressive symptoms (p < 0.01 for all). However, after adjusting for comorbidity, these associations were no longer statistically significant.
Anemia at baseline was associated with increased disability in instrumental activities of daily living during follow-up, the report indicates. Incident anemia was tied increased disability in basic activities of daily living.
Prevalent and incident anemia were both associated with increased mortality. Moreover, unlike many of the associations with functional status, the ties between anemia and death remained significant even after accounting for comorbid illness and other factors, such as gender, education level, income, and residence in a long-term care facility.
Prevalent and incident anemia were associated with 41% and 108% increased risks of death, respectively, the authors note.
In an accompanying editorial, Dr. A. Mark Clarfield, from McGill University, Montreal, and Ora Paltiel, from Hadassah-Hebrew University, Jerusalem, comment that further research is needed to determine if anemia actually causes increased mortality and to determine if treating anemia in very elderly people improves survival and functional outcomes.