Abstract
BACKGROUND: Chronic respiratory diseases (CRPD) are a global health threat characterized by oxidative stress, systemic inflammation, hypoxemia, and respiratory distress. Inflammatory indicators such as hemoglobin-to-red blood cell distribution width ratio (HRR) have been explored in relation to diseases of the respiratory system, but the correlation between HRR and pulmonary function has not been established. As part of this study, a representative sample of the National Health and Nutrition Examination Survey (NHANES) respondents aged 40 or over was used to examine the correlation between HRR and pulmonary function indices. METHODS: Data from the 2007-2012 NHANES were used for this study. HRR and four pulmonary function parameters were compared using regression and subgroup analyses. The Restricted Cubic Spline (RCS) model was employed to find out if there are any non-linear relationships between these associations. Multiple sensitivity analyses were used to verify the correlation between the two. RESULTS: After adjusting for confounding variables, the data showed that for each unit increase in HRR among the population as a whole, for each unit increase in HRR, FVC increased by 0.11, FEV1 increased by 0.22, peak expiratory flow (PEF) increased by 0.24 and forced expiratory flow at 25-75% (FEF25-75%) was elevated by 0.49. In addition, we determined linear and positive correlations between FVC, FEV1, PEF or PEF 25-75% and HRR by constructing the RCS model curves. The positive correlation between HRR and pulmonary function parameters was affirmed through sensitivity analysis. Furthermore, except for the PEF 25-75%, FVC, FEV1, PEF all showed a significant upward trend with the increase of HRR in non-Hispanic white female population. CONCLUSION: According to our study, HRR was positively correlated with FVC, FEV1, PEF, and PEF25-75% in a middle-aged and older adult US population. It would be useful to study the specific impact of HRR on pulmonary function and to investigate the potential pathophysiological mechanisms that might link them.