Longitudinal association between hemoglobin and lung function with insights into incidence of chronic obstructive pulmonary disease

<bold>Background:</bold> The evidence for a long-term association between hemoglobin (Hb) levels and lung function in a healthy population is scarce. We investigated the longitudinal relationship between Hb and lung function in a community-based population cohort in South Korea. <bold>Methods:</bold> A total of 4468 patients were followed biennially for up to 8 years. We employed linear mixed regression analysis to evaluate longitudinal associations between Hb levels and lung function. Additionally, we used a generalized estimating equation to calculate the odds ratio (OR) of chronic obstructive pulmonary disease (COPD) according to Hb levels. <bold>Result:</bold> In the total participants, higher Hb levels were associated with increased lung function (estimated value in FVC: 11.7 mL, FEV1: 10.7mL, FEV1/FVC: 0.11%; all P < 0.001) and a decreased incidence of COPD (OR = 0.85, 95% CI 0.77-0.93, P < 0.001). In subgroup analysis in men, lung functions were positively associated with Hb levels (estimated value in FVC: 16.7 mL, FEV1: 15.5 mL, FEV1/FVC: 0.18%; all P < 0.001) and decreased incidence of COPD (OR = 0.83, 95% CI 0.75-0.92, P < 0.001). In postmenopausal women, higher Hb levels were associated with increased lung function (estimated value in FVC: 11.4mL, P < 0.001; FEV1: 9.5mL, P < 0.001; FEV1/FVC: 0.09%, P < 0.038), but the incidence of COPD showed no statistical significance (OR = 0.81, 95% CI 0.63-1.05, P = 0.110). <bold>Conclusion:</bold> Decreased Hb level was associated with reduced lung function and an increased incidence of COPD. These findings were more pronounced in men and also observed in postmenopausal women.