Table 1:
Characteristics of the study population according to the tertiles of serum-free kynurenine.
| Total | Tertiles of serum-free kynurenine (mg/L) | |||||
|---|---|---|---|---|---|---|
| T1 < 0.11 | T2 [0.11–0.16] | T3 >=0.16 | ||||
| Characteristics | N = 2406a | (n = 802)a | (n = 801)a | (n = 803)a | P-valueb | Missing data |
| Age at baseline (years) | 68 [60–76] | 67 [58–74] | 69 [60–76] | 69 [62- 77] | <0.0001 | 0% |
| Men | 66% | 68% | 67% | 63% | 0.07 | 0% |
| eGFR at baseline (ml/min/1.73 m2) | 25 [18–33] | 31 [24–40] | 25 [19–32] | 20 [15–26] | <0.0001 | 0% |
| Albumin- or protein-to-creatinine ratio (mg/g) | 104 [21–491] | 57 [14–345] | 104 [23–440] | 198 [34–721] | <0.0001 | 11.5% |
| History of acute kidney injury | 23% | 20% | 24% | 27% | 0.005 | 7.2% |
| Smoking statusNever-smokerCurrent smokerFormer smoker | 40%13%47% | 41%13%46% | 40%13%46% | 40%10%50% | 0.3 | 0.6% |
| Systolic blood pressure (mmHg) | 140 [128- 153] | 138 [127–151] | 140 [129- 152] | 140 [130–155] | 0.014 | 0.5% |
| Diabetes | 41% | 35% | 41% | 47% | <0.0001 | 0.2% |
| Dyslipidemia | 74% | 70% | 73% | 77% | 0.008 | 0.4% |
| History of cardiovascular disease | 52% | 46% | 51% | 60% | <0.0001 | 0.5% |
| Serum bicarbonate (mmol/L) | 25 [23–27] | 25.4 [23–27.4] | 25 [22.4–27] | 24.5 [22–27] | <0.0001 | 8.8% |
| Serum albumin (g/L) | 40.4 [38–43] | 41 [38.4–43.2] | 41 [38–43] | 40 [37–42] | <0.0001 | 14.5% |
| Hemoglobin (g/dL) | 13 [11.8–14.2] | 13.4[12.3–14.5] | 13 [11.9–14.2] | 12.6 [11.5–13.7] | <0.0001 | 0.9% |
| High-sensitivity C-reactive protein (mg/L) | 2.4 [1.1–5.1] | 2 [0.9–4.1] | 2.3 [1.1–4.8] | 2.9 [1.3–6.5] | <0.0001 | 5.4% |
| Body mass index (kg/m²) | 27.9 [24.7–31.7] | 27.2 [24.3–30.8] | 27.8 [24.5–31.6] | 28.8 [25.4–32.8] | <0.0001 | 1.9% |
| PPI prescription at baseline | 32% | 30% | 31% | 36% | 0.01 | 0.2% |
| Diuretics prescription at baseline | 52% | 43% | 51% | 63% | <0.0001 | 0.3% |
| Antihypertensive drugs prescription at baseline | 2243 (94%) | 722 (91%) | 753 (94%) | 768 (96%) | <0.0001 | 0.3% |
| Lipid-lowering drugs prescription at baseline | 1520 (63%) | 472 (59%) | 510 (64%) | 538 (67%) | 0.005 | 0.3% |
| Antidiabetic drugs prescription at baseline | 820 (34%) | 231 (29%) | 275 (34%) | 314 (39%) | <0.001 | 0.3% |
| Free tryptophan (mg/L) | 0.9 [0.7–1.2] | 0.7 [0.6–0.9] | 0.9 [0.8–1.1] | 1.2 [0.9–1.5] | <0.0001 | 0% |
| Total tryptophan (mg/L) | 12 [10–15] | 12 [10–15] | 12.6 [10–15] | 12 [9.9–14.6] | 0.1 | 0% |
| Free kynurenine (mg/L) | 0.1 [0.09–0.2] | 0.07 [0.06–0.08] | 0.12 [0.11–0.14] | 0.2 [0.18–0.26] | – | 0% |
| Total kynurenine (mg/L) | 1.2 [0.9–1.6] | 0.9 [0.7–1.2] | 1.2 [0.9–1.6] | 1.4 [1.2–1.8] | <0.0001 | 0% |
a
Median [Q1–Q3]; %
b
Kruskal–Wallis rank sum test; Pearson's chi-squared test eGFR: estimated glomerular filtration rate; PPI: proton pump inhibitor.
Statistically significant p-values are given in bold type.