Background and objectives: Elevated circulating fibroblast growth factor 23 (FGF23) predicts progression of CKD, but it is unknown whether circulating FGF23 independently predicts incident CKD. This study aimed to determine whether circulating FGF23 predicts incident CKD in community-dwelling women.
Design, setting, participants, & measurements: This study examined the relationship of intact serum FGF23, 1,25-dihydroxyvitamin D(3) (1,25[OH](2)D), 25-hydroxyvitamin D (25[OH]D), parathyroid hormone, calcium, and phosphate with prevalent and incident CKD in 701 disabled women, ≥65 years of age, from the Women's Health and Aging Study I in Baltimore, Maryland, from 1993 to 1997. Incident CKD was defined as a low estimated GFR (eGFR) <60 ml/min per 1.73 m(2) only, low eGFR <60 ml/min per 1.73 m(2) and a ≥25% decline in eGFR from baseline, and an increase in serum creatinine (≥0.4 mg/dl) at follow-up.
Results: At baseline, 381 women (54.3%) had stage 3 CKD. Of 307 women without CKD at baseline, 63 (20.5%) developed stage 3 CKD over 24 months of follow-up. After excluding prevalent cases of CKD, FGF23 (per 1 SD increase) was associated with incident stage 3 CKD (hazard ratio [HR], 1.51; 95% confidence interval [95% CI], 1.06, 2.16; P=0.02), low and declining eGFR (HR, 3.69; 95% CI, 1.68, 8.11; P=0.001), and increase in serum creatinine (HR, 5.35; 95% CI, 1.27, 22.54; P=0.02) in respective multivariable Cox proportional hazards models adjusting for baseline eGFR, age, race, phosphate, 1,25-dihydroxyvitamin D(3), parathyroid hormone, and other potential confounders.
Conclusions: Elevated FGF23 is an independent risk factor for incident CKD in older, disabled, community-dwelling women.