The association of hemoglobin concentration with disability and decreased mobility among older Brazilians

Objective: To examine the association between hemoglobin concentration and disability and mobility difficulty among older adults living in São Paulo, Brazil. Design: Cross-sectional study. Setting: Population-based study conducted in São Paulo, Brazil. Participants: Adults age 60 and over (n=1,256) from the third data collection wave of the SABE Study (Health, Well-being, and Aging) conducted in 2010. Measurements: Two outcome measures were included in the analyses: 1) a difficulty to perform at least one of the instrumental activities of daily living (IADL) and 2) mobility difficulty, which was assessed using the Short Physical Performance Battery (SPPB). Logistic regression models assessed the association between hemoglobin and each of the outcome measures. All analyses were adjusted for sociodemographic and health characteristics. Results: The prevalence of IADL disability was 26.8% and 10.7% of participants had mobility difficulty. The mean hemoglobin concentration was significantly lower in older adults who already presented disability (13.7g/dL versus 14.4g/dL among independent elderly) or decreased mobility (13.4g/dL versus 14.3g/dL among elderly with preserved mobility). Higher values of hemoglobin concentration were associated with lower the risk of IADL disability (OR=0.88; p=0.04) and mobility difficulty (OR=0.81; p=0.02). Hemoglobin concentrations showed a dose-response effect in the probability of each outcome. Conclusions: Lower hemoglobin concentration was associated with a higher probability of IADL disability and mobility difficulty, showing a clear dose-response effect.