Longitudinal association between kidney and lung function in the Korean general population.

Background: The longitudinal relationship between kidney and lung function remains poorly understood. We examined the longitudinal association between estimated glomerular filtration rate (eGFR) and lung function in a Korean population with normal kidney and lung function from 2005 to 2014.

Methods: We recruited participants from the Ansan and Ansung cohorts of the Korean Genome and Epidemiology Study. Linear mixed-effects models were employed to analyze the relationship between eGFR and lung function parameters such as forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and FEV1/FVC ratio. The models were adjusted for confounding factors, including age, height (or body mass index), residential area, smoking status, and baseline lung function (or eGFR).

Results: A total of 4,388 participants were followed for up to 8 years, revealing a significant bidirectional relationship between decreases in eGFR and declines in lung function in both males and females. The results remained consistent after adjusting for potential confounders, including physical activity, socioeconomic status, alcohol consumption, systolic blood pressure, hypertension, diabetes mellitus, total cholesterol levels, hemoglobin levels, and proteinuria.

Conclusion: Our findings suggest a bidirectional long-term relationship between kidney and lung function in the Korean general population, although the direction of causality remains unclear. This study highlights the importance of monitoring both kidney and lung health, particularly in an aging population.