Association between pulmonary function and rapid kidney function decline: a longitudinal cohort study from CHARLS

Background Pulmonary function has been reported to be associated with chronic kidney disease. However, the relationship between lung function and rapid kidney function decline remains unclear.Methods Participants aged >= 45 years with complete data from the 2011 and 2015 interviews of the China Health and Retirement Longitudinal Study (CHARLS) were included. Lung function, assessed by peak expiratory flow (PEF), and kidney function, assessed by estimated glomerular filtration rate (eGFR), were tested at the baseline and endpoint surveys. Rapid kidney function decline was defined as a decrease in eGFR >= 3 mL/min/1.73 m(2)/year, and Delta eGFR represented the difference between baseline and endpoint eGFR. Multivariate logistic regression models and linear regression models were employed to evaluate the association between PEF and the risk of rapid eGFR decline, as well as the correlation between PEF and Delta eGFR.Results A total of 6159 participants were included, with 1157 (18.78%) individuals experiencing a rapid decline in eGFR. After adjusting for potential covariates, higher baseline PEF (Quartile 4 vs Quartile 1, OR=0.95, 95% CI 0.92 to 0.98) and elevated PEF % predicted (OR=0.96, 95% CI 0.94 to 0.99) were found to be associated with a lower risk of rapid eGFR decline. Delta eGFR decreased by 0.217 and 0.124 mL/min/1.73 m(2) for every 1 L/s increase in baseline PEF (beta (95% CI): -0.217 (-0.393 to -0.042)) and 10% increase in PEF % predicted (beta (95% CI): -0.124 (-0.237 to -0.011)), respectively. During the follow-up period, Delta eGFR decreased as PEF increased over time among participants in Quartile 1 (beta per 1 L/s increase in Delta PEF=-0.581, 95% CI -1.003 to -0.158; beta per 10% increase in Delta PEF % predicted=-0.279, 95% CI -0.515 to -0.043).Conclusions Higher PEF was associated with a slower longitudinal eGFR decline in middle-aged and older adults.