Associations between hemoglobin levels and sarcopenia and its components: Results from the I-Lan longitudinal study

Background: As a biomarker for anemia and nutritional status, hemoglobin may play various roles in the development of sarcopenia, but studies evaluating these roles are scarce. Hence, this study aimed to explore the associations between hemoglobin levels and sarcopenia and its components and to determine optimal cutoffs of hemoglobin for identifying sarcopenia. Methods: Data from 730 participants identified from the I-Lan Longitudinal Aging Study were retrieved. Anemia was defined by the World Health Organization criteria as a hemoglobin level <13 g/dL in men and <12 g/dL in women, and anemia status was divided into 5 groups (1 g/dL below cutoff, 0–1 g/dL below cutoff, 0–1 g/dL above cutoff, 1–2 g/dL above cutoff, and 2 g/dL above cutoff) for trend analysis. Sarcopenia was defined by the Asian Working Group for Sarcopenia 2019 criteria. Results: In total, 118 (16.2%) participants were anemic, and 62 (8.5%) participants were sarcopenic. A higher hemoglobin level was significantly associated with faster gait speed (p-trend, 0.037) and stronger handgrip strength (p-trend, 0.003). Anemia was significantly associated with sarcopenia (OR: 2.4, 95% CI: 1.2–4.9), weakness (OR: 1.6, 95% CI: 1.0–2.5) and slowness (OR: 2.0, 95% CI: 1.1–3.4). Stronger correlations between anemia and sarcopenia were found in men and those with severe disease burden. Conclusions: Hemoglobin levels were independently associated with sarcopenia, and the associations were stronger for muscle function than for muscle mass and in men than in women. Older adults with anemia had a higher risk of sarcopenia and muscle weakness, and further intervention studies are needed to clarify the causal relationship between anemia and sarcopenia.