Effect of anemia and comorbidity on functional status and mortality in old age: results from the Leiden 85-plus Study

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Abstract
Background: There is limited insight into the attributable effect of anemia and comorbidity on functional status and mortality in old age. Methods: The Leiden 85-plus Study is a population-based prospective follow-up study of 562 people aged 85 years. Anemia was defined according to World Health Organization criteria. We measured 3 parameters of functional status at baseline and annually thereafter for 5 years: disability in basic and instrumental activities of daily living, cognitive function and the presence of depressive symptoms. We obtained mortality data from the municipal registry. Results: The prevalence of anemia at baseline was 26.7% (150/562). Participants who had anemia at baseline had more disability in activities of daily living, worse cognitive function and more depressive symptoms than participants without anemia at baseline (p ≤ 0.01). These differences disappeared after adjustment for comorbidity. After adjustment for comorbidity in the prospective analyses, anemia at baseline was associated with an additional increase in disability in instrumental activities of daily living during follow-up; incident anemia during follow-up (n = 99) was associated with an additional increase in disability in basic activities of daily living. Prevalent and incident anemia were both associated with an increased risk of death, even after we adjusted for sex, education level, income, residence in a long-term care facility, C-reactive protein level, creatinine clearance and the presence of disease (hazard ratio for prevalent anemia 1.41, 95% confidence interval [CI] 1.13 to 1.76; hazard ratio for incident anemia 2.08, 95% CI 1.60 to 2.70). Interpretation: Anemia in very elderly people appears to be associated with an increased risk of death, independent of comorbidity. However, the associated functional decline appears to be attributed mainly to comorbidity.