Table 3.

Factors associated with serum phosphate levels using linear regression analyses.

Variables	Simple linear regression		Multiple linear regression†
	β (95% CI)	P value	adjusted β (95% CI)	P value
Age (year)	− 0.004 (− 0.008, − 0.001)	0.016	− 0.005 (− 0.008, − 0.001)	0.009
Sex (male)	0.071 (− 0.024, 0.165)	0.144	− 0.010 (− 0.110, 0.091)	0.852
BMI (kg/m2)	0.018 (0.009, 0.027)	< 0.001	0.016 (0.006, 0.026)	0.001
Dialysis vintage (month)*	0.018 (− 0.030, 0.065)	0.465	–
Parathyroidectomy (yes)	− 0.006 (− 0.136, 0.123)	0.923	–
Adherence to phosphate binder (yes)	− 0.158 (− 0.252, − 0.063)	0.001	− 0.184 (− 0.276, − 0.092)	< 0.001
Kt/V	− 0.214 (− 0.327, − 0.101)	< 0.001	− 0.223 (− 0.357, − 0.089)	0.001
nPNA (g/kg)	0.164 (0.000, 0.329)	0.050	0.242 (0.073, 0.411)	0.005
Total protein (g)*	0.205 (0.063, 0.346)	0.005	–
Animal protein (g)*	0.031 (0.003, 0.059)	0.029	0.018 (− 0.034, 0.071)	0.498
Plant protein (g)*	0.052 (− 0.016, 0.121)	0.135	0.033 (− 0.034, 0.101)	0.331
Total phosphate (mg)*	0.124 (− 0.010, 0.258)	0.069	0.015 (− 0.126, 0.157)	0.830
Animal organic phosphate (mg)*	0.016 (− 0.004, 0.037)	0.122	− 0.005 (− 0.043, 0.033)	0.782
Plant organic phosphate (mg)*	0.007 (− 0.048, 0.062)	0.810	–
Inorganic phosphate (mg)*	0.000 (− 0.015, 0.014)	0.946	–
Phosphate to protein ratio (mg/g)*	− 0.131 (− 0.334, 0.072)	0.205	–

nPNA, normalization of protein nitrogen appearance.

*Data was log-transformed.

“–” indicates variables not included in the multiple linear regression analysis; only variables with p-value < 0.25 in the simple linear regression were carried into the multiple linear regression analysis, “total protein” was excluded as it was a sum of both “animal protein” and “plant protein” while “phosphate to protein ratio” was excluded in the analysis due to collinearity. Bold values denote statistical significance at p-value < 0.05.

^†The highest variance inflation factor was 3.960.