Table 1.

Demographic, clinical, and laboratory characteristics of the entire study cohort and according to quartiles of phosphorus

VariableOverall (n = 1716)Quartiles of Serum PhosphorusP Trend
P < 3.3 mg/dl (n = 382)P ≥ 3.3 mg/dl and < 3.8 mg/dl (n = 426)P ≥ 3.8 mg/dl and < 4.3 mg/dl (n = 479)P ≥ 4.3 (n = 429)
Demographic variables
    age (years)70.0 (13.6)72.0 (11.3)71.6 (12.8)69.6 (13.9)67.2 (15.2)<0.001
    male gender (%)66.284.368.561.453.1<0.001
Clinical variables
    hypertension (%)96.396.197.19696.20.78
    diabetes mellitus (%)29.020.225.234.034.80.001
    COPD (%)11.612.912.811.19.90.47
    CVD (%)36.739.839.435.732.60.10
    CKD (%)
        stage 337.037.130.823.78.3<0.001
        stage 446.617.025.032.825.2<0.001
        stage 516.23.610.823.362.4<0.001
Laboratory variables
    phosphorus (mg/dl)3.9 (2.13)2.9 (0.3)3.5 (1.4)4.0 (0.16)5.2 (3.9)<0.001
    calcium (mg/dl)9.0 (0.93)9.1 (1.0)9.0 (0.9)9.0 (0.9)8.8 (0.9)0.006
    iPTH (ng/ml)178 [73 to 178]98 [68 to 169]119 [71 to 185]117 [75 to 203]173 [96 to 334]<0.001
    hemoglobin (mg/dl)12.5 (3.3)13.2 (1.7)12.6 (1.6)12.2 (5.7)11.6 (1.6)<0.001
    total cholesterol (mg/dl)192 (42)191 (41)191 (40)193 (45)193 (43)0.91
    HDL cholesterol (mg/dl)51.9 (15)49.5 (13)51.4 (14)53.1 (16)53.8 (16)0.01
    triglycerides (mg/dl)149 (81)155 (83)140 (74)152 (83)149 (81)0.09
    uric acid (mg/dl)6.3 [5.2 to 7.4]6.3 [5.6 to 7.4]6.2 [5.6 to 7.4]6.3 [5.1 to 7.3]6.2 [5.2 to 7.6]0.55
    glucose (mg/dl)108 (38)106 (34)107 (41)112 (42)105 (34)0.08
    creatinine (mg/dl)2.3 [1.8 to 3.1]1.9 [1.6 to 2.3]2.0 [1.7 to 2.7]2.4 [1.8 to 2.9]3.2 [2.3 to 4.4]<0.001
    GFR (mg/min per 1.73 m2)25 [18 to 34]32 [25 to 40]28 [21 to 36]24 [18 to 32]17 [12 to 24]<0.001
Concomitant medications
    calcium salts15.96.49.414.632.5<0.001
    vitamin D16.19.813.516.723.9<0.001
    ARB31.732.131.333.529.90.71
    ACE inhibitors46.747.249.047.443.30.39
    other hypertensive medications24.519.425.024.728.50.03
  • Data are expressed as mean (standard deviation) or median [IQR] when appropriate. ARB, Angiotensin Receptor Blockers.