Association between anemia and physical disability in older patients: role of comorbidity

In older persons, anemia is a common medical disorder and is often associated with comorbidity and poor health outcomes. We evaluated the relationship between anemia and physical disability in a sample of older hospitalized patients, taking into account the role of comorbidity.

Cross-sectional analysis of the baseline data of the Italian Group of Pharmacoepidemiology in the Elderly Study. Patients aged 65 years or older (n=10,903), admitted to participating centers in the 1993-1998 survey period, were included. Anemia was defined according to the World Health Organization (WHO) criteria; physical disability was defined as need for assistance in performing at least one Activity of Daily Living (ADL) in the week before admission. Comorbidity was ascertained using the Charlson Index.

Prevalence of anemia was 41.1%. In the unadjusted analysis, anemia was associated with increased likelihood of disability, in both women (Odds Ratio [OR]: 1.54; 95% Confidence Interval [CI]: 1.38-1.71) and men (OR 1.70; CI 1.52-1.90). After inclusion of demographics and life-style factors in multivariate analysis, the strength of association was only modestly attenuated, whereas nutritional factors and disease-related variables resulted in a greater reduction of the strength of association. In analyses stratified by comorbidity severity, the association between anemia and disability was statistically significant only in patients with the lowest comorbidity levels (p for anemia Charlson Index interaction term <0.05, in both women and men).

Among hospitalized subjects, anemia is associated with ADL disability. The disablement process associated with anemia may be partially explained by nutritional and disease-related factors. However, anemia appears to have an independent effect, particularly in subjects with low comorbidity.