Table 3.

Association of baseline variables with progression of kidney disease during the observation period using multiple Cox proportional hazards regression modelsa

Parameter Variable (increment)Model 1 Adjusted for Age and GenderModel 2 Adjusted for Age, Gender, and All Other Variables of This TableModel 3 Adjusted for Age, Gender, and All Other Variables Excluding FGF23
HR (95% CI)PHR (95% CI)PHR (95% CI)P
GFR (10 ml/min per 1.73 m2)0.668 (0.590 to 0.757)<0.0010.762 (0.666 to 0.872)<0.0010.736 (0.646 to 0.837)<0.001
Proteinuria (1 g/24 h)1.298 (1.023 to 1.647)0.0321.244 (0.921 to 1.679)0.1541.142 (0.862 to 1.515)0.354
Calcium (0.1 mmol/L)0.885 (0.746 to 1.049)0.1591.005 (0.877 to 1.153)0.9411.038 (0.925 to 1.164)0.525
Phosphate (0.1 mmol/L)1.091 (1.049 to 1.134)<0.0011.052 (0.952 to 1.162)0.3221.090 (0.995 to 1.194)0.063
Ca × P (0.1 mmol2/L2)1.041 (1.022 to 1.061)<0.0011.024 (0.981 to 1.068)b0.2791.041 (1.002 to 1.082)b0.040
Parathormone (1 pmol/L)1.041 (1.029 to 1.052)<0.0011.009 (0.993 to 1.025)0.2731.019 (1.005 to 1.033)0.008
FGF23 c-terminal (10 rU/ml)1.028 (1.021 to 1.034)<0.0011.014 (1.005 to 1.024)c0.002
FGF23 intact (10 pg/ml)1.111 (1.075 to 1.149)<0.0011.061 (1.018 to 1.106)c0.005
• a CI, confidence interval; HR, hazard ratio.

• b Because Ca × P is the product term of the variable calcium and phosphate, estimates for Ca × P were based on a model that did not include calcium and phosphate at the same time. In model 2, the estimate for Ca × P was adjusted for age, gender, GFR, proteinuria, parathormone, and c-terminal FGF23.

• c C-terminal FGF23 and intact FGF23 were not included at the same time but were adjusted for the same variables: Age, gender, GFR, proteinuria, calcium, phosphate, and parathormone.