Associations of ePTFp and serum FGF23 with eGFR slope were examined using multivariable regression analysis, adjusting for potential covariates at baseline, including age, sex, several comorbidities, current smoking status, eGFR, and urinary glomerular and tubular injury markers.<h4>Results</h4>Over 5 years, eGFR declined in participants with and without CKD, with a steeper decline in those with CKD. Here, FGF23 is linked to chronic kidney disease.