Table 1.
Baseline characteristics of the study patients with CKD 1,2 per protein intake.
| All | Protein Intake | p Value 3 | |||
|---|---|---|---|---|---|
| Very Low | Low | Moderate | |||
| (n = 352) | (n = 75) | (n = 161) | (n = 116) | ||
| Age (years) | 70.2 ± 11.4 | 70.6 ± 11.9 | 71.2 ± 11.0 | 68.6 ± 11.5 | 0.173 |
| ≤65 (n (%)) | 93 (26.4) | 16 (21.3) | 39 (24.2) | 38 (32.8) | 0.150 |
| >65 (n (%)) | 259 (73.6) | 59 (78.7) | 122 (75.8) | 78 (67.2) | |
| Male (n (%)) | 102 (29.0) | 24 (32.0) | 49 (30.4) | 29 (25.0) | 0.499 |
| Smoking (n (%)) | 58 (16.5) | 11 (14.7) | 26 (16.2) | 21 (18.1) | 0.614 |
| Body weight (kg) | 64.2 ± 13.6 | 60.6 ± 13.2 | 62.0 ± 12.3 | 69.6 ± 15.4 | <0.001 |
| BMI (kg/m2) 4 | 24.7 ± 4.4 | 23.1 ± 4.1 | 24.0 ± 3.5 | 26.9 ± 4.9 | <0.001 |
| Skeletal muscle mass (kg) 5,6 | 19.3 ± 6.5 | 14.7 ± 5.8 | 18.6 ± 5.1 | 23.2 ± 6.4 | <0.001 |
| CKD stage (n (%)) | |||||
| 3a | 20 (5.7) | 2 (2.7) | 6 (3.7) | 12 (10.3) | <0.001 |
| 3b | 72 (20.5) | 13 (17.3) | 29 (18.0) | 30 (25.9) | |
| 4 | 149 (42.3) | 23 (30.7) | 76 (47.2) | 50 (43.1) | |
| 5 | 111 (31.5) | 37 (49.3) | 50 (31.1) | 24 (20.7) | |
| eGFR (mL/min/1.73 m2) 7 | 22.9 ± 11.3 | 19.5 ± 11.0 | 21.8 ± 10.2 | 26.7 ± 12.0 | <0.001 |
| UPE (g/24 h) 6 | 0.81 (0.18 to 2.00) | 1.2 (0.26 to 2.61) | 0.73 (0.19 to 1.77) | 0.72 (0.16 to 1.83) | 0.089 |
| Serum phosphate (mg/dL) | 3.7 ± 0.8 | 3.9 ± 1.0 | 3.7 ± 0.7 | 3.7 ± 0.7 | 0.030 |
| Hypertension history (n (%)) | 315 (89.5) | 67 (89.3) | 145 (90.1) | 103 (88.8) | 0.943 |
| CVD history (n (%)) | 151 (42.9) | 34 (45.3) | 75 (46.6) | 42 (36.2) | 0.204 |
| Systolic blood pressure (mmHg) | 135 ± 21 | 137 ± 21 | 132 ± 21 | 137 ± 19 | 0.161 |
| LVEF (%) | 64.0 ± 10.6 | 63.8 ± 11.2 | 62.9 ± 10.9 | 65.6 ± 9.4 | 0.119 |
| DM history (n (%)) | 157 (44.6) | 38 (50.7) | 69 (42.9) | 50 (43.1) | 0.492 |
| Anemia (n (%)) | 177 (50.3) | 45 (60.0) | 85 (52.8) | 47 (40.5) | 0.021 |
| Serum albumin (g/dL) | 3.9 ± 0.4 | 3.7 ± 0.4 | 3.9 ± 0.5 | 4.0 ± 0.4 | <0.001 |
| CRP (mg/dL) | 0.09 (0.04 to 0.22) | 0.10 (0.03 to 0.35) | 0.07 (0.04 to 0.18) | 0.10 (0.04 to 0.20) | 0.330 |
| BNP (pg/mL) | 90 (39 to 221) | 132 (66 to 238) | 89 (42 to 224) | 62 (29 to 182) | 0.002 |
| Protein intake (g/day) 6,8 | 42.0 ± 10.7 | 30.5 ± 5.6 | 39.7 ± 5.9 | 52.7 ± 8.3 | <0.001 |
| Protein intake (g/kg IBW/day) 6,8 | 0.74 ± 0.08 | 0.52 ± 0.07 | 0.70 ± 0.06 | 0.93 ± 0.10 | <0.001 |
| Sodium intake (mmol/day) 6 | 62.9 ± 21.4 | 57.4 ± 21.3 | 61.7 ± 19.6 | 68.0 ± 22.7 | 0.002 |
1 Continuous and categorical values are shown as mean ± standard deviation (SD), median (interquartile range), or number (percentage). Bold values are statistically significant (p < 0.05). BMI, body mass index; BNP, brain natriuretic peptide; CKD, chronic kidney disease; CRP, C-reactive protein; CVD, cardiovascular disease; DM, diabetes mellitus; eGFR, estimated glomerular filtration rate; IBW, ideal body weight; LVEF, left ventricular ejection fraction; UPE, urinary protein excretion. 2 Ideal body weight was defined as a body mass index of 22 kg/m2. 3 Analysis of variance (ANOVA), Kruskal–Wallis test, or chi-square test was used to evaluate distribution. 4 The body mass index is the weight in kilograms divided by the square of the height in meters. 5 Total-body skeletal muscle mass = 21.8 × urinary creatinine excretion (g/24 h). 6 To reduce random error, mean values were calculated on the basis of two 24-h urine samples. 7 eGFR (mL/min/1.73 m2) = 194 × serum creatinine (−1.094) × age (−0.287) × 0.739 (if female). 8 Protein intake = 6.25 × (urinary nitrogen excretion (g/24 h) + weight (kg) × 0.031 (g/kg/day)).