Association between the Hemoglobin Levels and Hypertension in Relation to the BMI Status in a Rural Japanese Population: The Nagasaki Islands Study

OBJECTIVE: The hemoglobin levels and blood pressure has been reported in a few studies, and a positive association between the hemoglobin levels and the body mass index (BMI) status has also been documented. A higher BMI may therefore affect the association between the hemoglobin levels and hypertension. However, no published studies have examined this association in relation to the BMI status. The primary purpose of this study was to assess the association between the hemoglobin levels and hypertension in relation to the BMI status. METHODS: A cross-sectional study of 3,203 non-anemic subjects (1,191 men and 2,012 women, 30-79 years old) who were undergoing general health checkups was conducted. RESULTS: A positive association between the hemoglobin levels and hypertension was established for both men and women. For a one SD (standard deviation) increment in hemoglobin, the multivariable odds ratio (ORs) and 95% confidence interval (CIs) for hypertension were 1.21 (95%CI: 1.05-1.40) for men and 1.25 (95%CI: 1.13-1.39) for women. We also found that a significant association was confined to the participants with a BMI of <25 kg/m(2). Among the participants with a BMI of <25 kg/m(2), the multivariable ORs and 95% CIs for hypertension of a one SD increment in hemoglobin were 1.34 (95%CI: 1.12-1.60) for men and 1.31 (95%CI: 1.16-1.47) for women. Meanwhile, among those with a BMI of ≥25 kg/m(2), the corresponding values were 1.01 (95%CI: 0.79-1.30) and 1.09 (95%CI: 0.87-1.37). CONCLUSION: An independent positive association between the hemoglobin levels and the risk of hypertension was observed for both non-anemic Japanese men and women, confined to participants with a BMI of <25 kg/m(2).