Heterogeneity in the Association Between Anemia and Blood Pressure in a Rural Population

Abstract Objective The relationship between anemia and blood pressure remains incompletely understood, with previous studies reporting inconsistent findings. We examined whether the association between anemia and blood pressure differed across demographic groups in a rural population. Methods Clinical data from the Alabama State Health Information Exchange were analyzed for 1,212 adults (579 African American, 633 White). Multivariable linear models were used to examine the independent and interactive effects of anemia, race, gender, and age on systolic and diastolic blood pressure. Significant interactions were further evaluated using sex-stratified models and least squares mean comparisons. Results Significant race × anemia and race × gender × anemia interactions were observed for both systolic and diastolic blood pressure. Sex-stratified analyses showed that these interactions were driven primarily by men, whereas no significant race × anemia interactions were observed among women. Among men, African American participants with anemia had higher systolic and diastolic blood pressure than African American men without anemia, whereas the association between anemia and blood pressure was attenuated or reversed among White men. These findings demonstrate that the association between anemia and blood pressure is not uniform across the study population but differs across demographic groups. Conclusions We found evidence that the relationship between anemia and blood pressure is heterogeneous. Demographic variables identified this heterogeneity, but the mechanisms underlying these differences were not measured and likely involve differing biological, clinical, environmental, and psychosocial exposures rather than race itself. These findings highlight the importance of considering effect modification when evaluating the relationship between anemia and hypertension and suggest that future studies should directly measure the biological and social factors underlying this heterogeneity to better understand hypertension risk.