Fig. 4.

Hazard ratio for death associated with increasing FGF23 concentrations in patients with pre-dialysis CKD. The median fibroblast growth factor 23 (FGF-23) level within the lowest FGF-23 quartile (74 RU/mL) served as the referent value (hazard = 1.0). The model was stratified by center and adjusted for age; sex; race; ethnicity; estimated glomerular filtration rate; natural log-transformed urine albumin-to-creatinine ratio; hemoglobin; serum albumin; systolic blood pressure; body mass index; diabetes; smoking status; low-density lipoprotein; history of coronary artery disease, congestive heart failure, stroke, and peripheral vascular disease; use of aspirin, β-blockers, statins, and angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers; and serum calcium, phosphate, and natural log-transformed parathyroid hormone. Tick marks on the x-axis indicate individual observations at corresponding levels of FGF-23. The solid black line represents the multivariable-adjusted hazard of mortality as a function of the measured (nontransformed) FGF-23 level. The dashed lines indicate the 95% confidence intervals.