Table 3.
Baseline characteristics of RTR across tertiles of N1-MN excretion stratified by sex 1.
| Variable | Tertiles of Sex-Stratified N1-MN Excretion | p-Value 2 | ||
|---|---|---|---|---|
| T1 n = 219 |
T2 n = 221 |
T3 n = 220 |
||
| Males, μmol/day | <19.2 | 19.2–28.8 | >28.8 | |
| Females, μmol/day | <16.1 | 16.1–25.6 | >25.6 | |
| Male, n (%) | 126 (58) | 127 (58) | 126 (57) | - |
| Age, years | 54.6 ± 12.7 | 53.7 ± 13.1 | 50.7 ± 12.1 | 0.004 |
| BMI, kg/m2 | 25.8 (22.7–29.4) | 26.1 (23.3–29.0) | 26.0 (23.6–29.6) | 0.41 |
| Body surface area, m2 | 1.9 ± 0.2 | 1.9 ± 0.2 | 2.0 ± 0.2 | 0.13 |
| Lifestyle | ||||
| Current smoker, n (%) | 21 (10) | 25 (11) | 32 (15) | 0.26 |
| Alcohol consumption, g/day | 0.5 (0.0–7.0) | 3.2 (0.1–11.3) | 6.7 (0.8–20.9) | <0.001 |
| Vegetarian, n (%) | 7 (3) | 2 (1) | 3 (1) | 0.16 |
| Dietary intake | ||||
| Energy, kcal/day | 2065 ± 586 | 2197 ± 675 | 2285 ± 647 | 0.002 |
| Tryptophan, mg/day | 1001 ± 253 | 1063 ± 273 | 1112 ± 274 | <0.001 |
| Niacin, mg/day | 16.6 ± 4.9 | 17.6 ± 4.8 | 19.5 ± 5.5 | <0.001 |
| Plasma vitamin B6, nmol/L | 20.3 (14.0–39.0) | 29.5 (19.0–47.0) | 39.0 (22.0–65.0) | <0.001 |
| Hemodynamic | ||||
| Systolic blood pressure, mmHg | 139 ± 18 | 134 ± 18 | 135 ± 16 | 0.01 |
| Diastolic blood pressure, mmHg | 83 ± 11 | 82 ± 12 | 83 ± 11 | 0.20 |
| Mean arterial pressure, mmHg | 109 ± 15 | 106 ± 15 | 106 ± 14 | 0.07 |
| Heart rate, beats per minute | 69 ± 11 | 68 ± 12 | 68 ± 12 | 0.52 |
| Antihypertensive use, n (%) | 199 (91) | 193 (87) | 189 (86) | 0.26 |
| Lipids | ||||
| Total cholesterol, mmol/L | 5.1 ± 1.2 | 5.2 ± 1.1 | 5.0 ± 1.1 | 0.36 |
| HDL, mmol/L | 1.3 (1.0–1.6) | 1.3 (1.1–1.6) | 1.3 (1.1–1.7) | 0.06 |
| LDL, mmol/L | 3.0 ± 0.9 | 3.1 ± 0.9 | 2.9 ± 0.9 | 0.31 |
| Triglycerides, mmol/L | 1.7 (1.3–2.3) | 1.7 (1.3–2.3) | 1.6 (1.1–2.2) | 0.03 |
| Statin, n (%) | 122 (56) | 115 (52) | 112 (51) | 0.55 |
| Glucose homeostasis | ||||
| Glucose, mmol/L | 5.3 (4.8–6.0) | 5.3 (4.8–5.9) | 5.2 (4.7–6.2) | 0.58 |
| HbA1c, (%) | 5.8 (5.5–6.3) | 5.9 (5.6–6.1) | 5.7 (5.4–6.1) | 0.05 |
| Diabetes, n (%) | 58 (27) | 44 (20) | 50 (23) | 0.26 |
| Antidiabetic, n (%) | 41 (19) | 28 (13) | 27 (12) | 0.10 |
| Other serum parameters | ||||
| Hs-CRP, mg/L | 1.7 (0.8–5.3) | 1.6 (0.6–3.8) | 1.4 (0.7–4.6) | 0.42 |
| Phosphate, mmol/L | 1.0 ± 0.2 | 1.0 ± 0.2 | 0.9 ± 0.2 | 0.01 |
| Immunosuppressant medication | ||||
| Prednisolon dose, mg/day | 10 (7.5–10) | 10 (7.5–10) | 10 (7.5–10) | 0.18 |
| Calcineurin inhibitor, n (%) | 136 (62) | 125 (57) | 112 (51) | 0.06 |
| Cyclosporine, n (%) | 87 (40) | 82 (37) | 84 (38) | 0.85 |
| Azathioprine, n (%) | 35 (16) | 36 (16) | 41 (19) | 0.72 |
| Proliferation inhibitor, n (%) | 171 (78) | 186 (84) | 191 (87) | 0.04 |
| Other medication | ||||
| Acetylsalicylic acid, n (%) | 55 (25) | 47 (21) | 25 (11) | 0.001 |
| Anticonvulsant, n (%) | 7 (3) | 5 (2) | 7 (3) | 0.80 |
| Proton pump inhibitor, n (%) | 127 (58) | 107 (48) | 92 (42) | 0.003 |
| Diuretic, n (%) | 104 (48) | 79 (36) | 78 (36) | 0.01 |
| Kidney function | ||||
| Serum creatinine, μmol/L | 138 (104–189) | 122 (101–153) | 114 (94–140) | <0.001 |
| Cystatin C, mg/L | 2.0 (1.4–2.8) | 1.6 (1.3–2.1) | 1.4 (1.2–1.9) | <0.001 |
| eGFR, ml/min/1.73 m2 | 39.0 ± 18.7 | 45.8 ± 16.9 | 52.7 ± 18.0 | <0.001 |
| Proteinuria ≥ 0.5 g/day, n (%) | 55 (25) | 39 (18) | 38 (17) | 0.07 |
| Kidney transplantation | ||||
| Time since transplantation, years | 5.6 (1.7–12.9) | 5.0 (1.5–11.0) | 6.5 (2.9–12.3) | 0.16 |
| Donor | ||||
| Age, years | 46 (33–54) | 47 (29–57) | 43 (29–53) | 0.22 |
| Male, n (%) | 104 (48) | 110 (50) | 112 (51) | 0.60 |
| Post mortem status, n (%) | 161 (74) | 143 (65) | 121 (55) | <0.001 |
| Primary kidney disease | ||||
| Primary glomerular disease, n (%) | 48 (22) | 67 (30) | 71 (32) | 0.04 |
| Glomerulonephritis, n (%) | 12 (6) | 17 (8) | 21 (10) | 0.27 |
| Tubulointerstitial disease, n (%) | 27 (12) | 30 (14) | 20 (9) | 0.32 |
| Polycystic renal disease, n (%) | 52 (24) | 45 (20) | 40 (18) | 0.35 |
| Dysplasia and hypoplasia, n (%) | 9 (4) | 10 (5) | 9 (4) | 0.97 |
| Renovascular disease, n (%) | 17 (8) | 8 (4) | 11 (5) | 0.15 |
| Diabetic nephropathy, n (%) | 15 (7) | 7 (3) | 13 (6) | 0.20 |
| Other or unknown cause, n (%) | 39 (18) | 36 (16) | 35 (16) | 0.85 |
1 Data are presented as mean ± SD, median (IQR) and absolute number (percentage) for normally distributed, skewed and nominal data, respectively. 2 p-value for difference was tested by ANOVA and Kruskal-Wallis tests for normally and skewed distributed continuous variables, respectively, and Chi-Square tests for nominal variables. eGFR, estimated glomerular filtration rate; HbA1c, hemoglobin A1c; hs-CRP, high-sensitivity C-reactive protein; N1-MN, N1-methylnicotinamide; RTR, renal transplant recipients.