Higher baseline fibroblast growth factor 23 levels were associated with higher risk of incident CKD in unadjusted and demographics-adjusted models , but the effect was attenuated after additional adjustment for clinical risk factors and baseline eGFR ( hazard ratio per SD of natural log fibroblast growth factor 23 , 1.09 ; 95 % confidence interval , 0.94 to 1.27 ) , which was the strongest predictor of incident CKD .