Table 1.
Baseline characteristics of patients in the DPI tertile group.
| Tertile of DPI | p-trend | |||
|---|---|---|---|---|
| 1T (n = 533) | 2T (n = 512) | 3T (n = 527) | ||
| Age (years) | 54.1 ± 12.0 | 54.0 ± 12.1 | 54.7 ± 12.0 | 0.35 |
| Male sex (%) | 58.9 | 61.3 | 69.1 *,† | 0.001 |
| Current smoking (%) | 15.6 | 16.8 | 14.1 | 0.50 |
| Alcohol drinking (%) | 39.9 | 43.7 | 53.7 *,† | <0.001 |
| Hypertension (%) | 94.9 | 94.9 | 95.6 | 0.60 |
| Diabetes (%) | 24.7 | 23.7 | 25.5 | 0.78 |
| Cause of CKD | ||||
| DMN (%) | 25.0 | 23.0 | 21.1 | 0.14 |
| HN (%) | 18.6 | 21.9 | 21.9 | 0.19 |
| GN (%) | 34.1 | 32.4 | 32.1 | 0.48 |
| Others (%) | 22.3 | 22.7 | 24.9 | 0.32 |
| BUN (mmol/L) | 9.9 ± 5.9 | 9.9 ± 5.3 | 9.5 ± 4.9 | 0.19 |
| Cr (μmol/L) | 175.5 ± 109.7 | 154.2 ± 86.3 * | 132.9 ± 67.4 *,† | <0.001 |
| eGFR (ml/min/1.73 m2) | 49.2 ± 30.9 | 53.9 ± 30.5 * | 60.8 ± 29.3 *,† | <0.001 |
| UPCR (g/g Cr) | 0.54 (0.17–1.63) | 0.45 (0.12–1.40) * | 0.40 (0.12–1.03) * | 0.001 |
| Advanced CKD (%) | 55.3 | 47.7 * | 36.6 *,† | <0.001 |
| DPI (g/kg/day) | 0.78 ± 0.12 | 1.04 ± 0.07 * | 1.48 ± 0.41 *,† | <0.001 |
| Bilirubin (μmol/L) | 11.1 ± 4.8 | 11.9 ± 5.1 * | 12.3 ± 5.3 * | <0.001 |
| BMI (kg/m2) | 23.4 ± 3.2 | 24.6 ± 3.2 * | 25.4 ± 3.1 *,† | <0.001 |
| FPG (mmol/L) | 5.9 ± 1.8 | 6.1 ± 2.2 | 6.1 ± 1.9 | 0.17 |
| Serum albumin (g/L) | 41.6 ± 4.5 | 42.3 ± 3.8 * | 42.5 ± 3.7 * | <0.001 |
| Cholesterol (mmol/L) | 4.4 ± 1.1 | 4.5 ± 1.0 | 4.5 ± 0.9 | 0.27 |
| Estimated SMM (kg) | 24.8 ± 5.6 | 28.0 ± 6.2 * | 32.0 ± 7.8 *,† | <0.001 |
| Hemoglobin (g/dL) | 12.4 ± 2.0 | 13.0 ± 2.0 * | 13.5 ± 1.9 *,† | <0.001 |
| hsCRP (nmol/L) | 5.7 (1.9–16.2) | 5.3 (1.9–14.1) | 6.7 (2.4–16.2) | 0.39 |
T, tertile; CKD, chronic kidney disease; DMN, diabetic nephropathy; HN, hypertensive nephropathy; GN, glomerulonephritis; BUN, blood urea nitrogen; Cr, creatinine; eGFR, estimated glomerular filtration rate; UPCR, urine protein-to-creatinine ratio; DPI, dietary protein intake; BMI, body mass index; FPG, fasting plasma glucose; SMM, skeletal muscle mass; hsCRP, high sensitivity C-reactive protein. Values are expressed as mean ± standard deviation for normally distributed continuous variables, median (interquartile range) for non-normally distributed continuous variables, and percentage for categorical variables. p-trends were analyzed by the linear term of the one-way ANOVA for normally distributed continuous variables, the Jonckheere–Terpstra test for non-normally distributed continuous variables, and a linear-by-linear association for categorical variables. Tertiles of DPI were <0.93 g/kg/day in the first tertile, 0.93–1.16 g/kg/day in the second tertile, and ≥1.16 g/kg/day in the third tertile, respectively. * and † indicate p < 0.05 when compared to 1T and 2T of the DPI group, respectively, using Bonferroni post-hoc analysis of one-way ANOVA for normally distributed continuous variables, the Mann–Whitney U test for non-normally distributed continuous variables w, and the chi-square test for categorical variables.