Higher hemoglobin levels are associated with better physical performance among older adults without anemia: a longitudinal analysis

BACKGROUND: Anemia is the most common hematological abnormality among older adults, and it is associated with decreased physical performance. But the role of hemoglobin in the absence of anemia remains unclear. Thus, this study aimed to assess the impact of hemoglobin levels on physical performance in Brazilian older adults without anemia. METHODS: The study is longitudinal in that it relies on two waves of the Saúde, Bem-Estar e Envelhecimento (SABE; Health, Well-being, and Aging) study: 2010 and 2015-2016. Mixed-effects linear regression was used to determine the effects of the hemoglobin concentrations on the Short Physical Performance Battery-SPPB over time among the 1,023 who had complete data and did not have anemia in 2010. In the follow-up, there were 567 without anemia. RESULTS: In analyses adjusted for age, education, comorbidities, body mass index, and physical inactivity, we found a differential association between hemoglobin concentration and SBBP by sex, with a positive interaction (β Hb*female= 0.20, 95% CI 0.04,0.37). At lower levels of hemoglobin, women have lower levels of SPPB than men, but at higher levels of hemoglobin concentration, there are no sex differences in physical performance. In addition, higher age was negatively associated with SPPB levels and cardiometabolic diseases, other diseases, and physical inactivity. Education was positively associated with physical performance. CONCLUSION: Our study demonstrates that higher hemoglobin levels were associated with better physical performance among older adults without anemia in Brazil. However, there were sex differences in this association. This finding is important because, in clinical practice, most health professionals focus on the World Health Organization definition of anemia. Our study suggests the importance of hemoglobin levels among older adults, even those without anemia, and highlights sex differences. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-022-02937-4.