Red cell distribution width, anemia, and lower-extremity physical function among rural-dwelling older adults

Background Elevated red cell distribution width (RDW) has been associated with degenerative conditions in aging. Aims We aimed to evaluate the associations of RDW and anemia with lower-extremity physical function among rural-dwelling older adults. Methods This population-based cross-sectional study included 5093 rural residents (age ≥ 60 years, 57.3% women) who participated in the MIND-China Study in Shandong. Data were collected via face-to-face interviews, clinical examinations, and laboratory tests. RDW was categorized according to quartiles and the lower-extremity physical function was assessed using the Short Physical Performance Battery (SPPB), Results Multiple linear regression analyses suggested that the fourth quartile of RDW (vs. first quartile) was associated with lower SPPB summary score (β-coefficient – 0.38; 95% CI – 0.58 to – 0.18) and lower scores in balance test (– 0.09; – 0.17 to – 0.01), chair stand test (– 0.17; – 0.27 to – 0.07), and walking speed test (– 0.12; – 0.19 to − 0.05). Anemia was associated with a multiple-adjusted β-coefficient of – 0.34 (– 0.52 to – 0.16) for SPPB summary score. Stratified analysis by anemia showed that there was a linear association between RDW and SPPB in individuals without anemia but a J-shaped association in individuals with anemia. Discussion This large-scale population-based study revealed the associations of high RDW and anemia with poor lower-extremity physical function among rural-dwelling Chinese older adults. These findings suggest that an elevated RDW might be a biochemical marker for poor lower-extremity physical function among older adults. Conclusions Anemia and an elevated RDW are associated with poor performance in lower-extremity physical function among rural-dwelling Chinese older adults.