Table 1.
Comparison of patient characteristics between the derivation and validation groups.
| Variable | Overall (n = 322) | Training (n = 225) | Testing (n = 97) | p |
|---|---|---|---|---|
| Demographics | ||||
| Age, years, median [IQR] | 68.00 [58.00, 79.00] | 67.00 [57.00, 78.00] | 68.00 [59.00, 80.00] | 0.33 |
| Male gender, n (%) | 209 (64.9) | 149 (66.2) | 60 (61.9) | 0.53 |
| Body mass index, n (%) | 0.87 | |||
| 18.5 ≤ BMI < 25 | 157 (48.8) | 113 (50.2) | 44 (45.4) | |
| BMI < 18.5 | 33 (10.2) | 22 (9.8) | 11 (11.3) | |
| 25 ≤ BMI < 30 | 111 (34.5) | 76 (33.8) | 35 (36.1) | |
| BMI ≥ 30 | 21 (6.5) | 14 (6.2) | 7 (7.2) | |
| Smoker, n (%) | 122 (37.9) | 90 (40.0) | 32 (33.0) | 0.29 |
| Comorbidities | ||||
| Moderate to severe heart failure, n (%) | 22 (6.8) | 15 (6.7) | 7 (7.2) | 1.00 |
| Hypertension, n (%) | 142 (44.1) | 103 (45.8) | 39 (40.2) | 0.42 |
| Diabetes, n (%) | 71 (22.0) | 46 (20.4) | 25 (25.8) | 0.36 |
| Pulmonary disease, n (%) | 29 (9.0) | 22 (9.8) | 7 (7.2) | 0.60 |
| Wasting of vitamin C by the kidney, n (%) | 19 (5.9) | 13 (5.8) | 6 (6.2) | 1.00 |
| Digestive system disorder, n (%) | 28 (8.7) | 22 (9.8) | 6 (6.2) | 0.40 |
| Cancer with chemotherapy, n (%) | 23 (7.1) | 16 (7.1) | 7 (7.2) | 1.00 |
| Primary diagnosis at admission to the ICU | ||||
| SOFA score, median [IQR] | 3.00 [2.00, 6.00] | 3.00 [2.00, 6.00] | 4.00 [2.00, 6.00] | 0.34 |
| Sepsis, n (%) | 0.73 | |||
| Sepsis, n (%) | 136 (42.2) | 93 (41.3) | 43 (44.3) | |
| Septic shock, n (%) | 36 (11.2) | 24 (10.7) | 12 (12.4) | |
| Source of infection, n (%) | 0.60 | |||
| Abdominal, n (%) | 80 (24.8) | 53 (23.6) | 27 (27.8) | |
| Others, n (%) | 56 (17.4) | 38 (16.9) | 18 (18.6) | |
| Abdominal surgery, n (%) | 126 (39.1) | 89 (39.6) | 37 (38.1) | 0.91 |
| Vascular disease, % | 27 (8.4) | 18 (8.0) | 9 (9.3) | 0.87 |
| Lab tests at admission to the ICU | ||||
| NLR, median [IQR] | 11.65 [6.92, 17.70] | 11.81 [6.86, 17.69] | 11.10 [7.06, 17.70] | 0.75 |
| CRP, mg/dL, median [IQR] | 2.66 [1.00, 7.14] | 2.66 [1.00, 7.17] | 2.82 [0.92, 7.07] | 0.77 |
| PCT, ng/ml, median [IQR] | 0.25 [0.07, 1.29] | 0.25 [0.07, 1.23] | 0.25 [0.07, 1.49] | 0.86 |
| Fib, g/L, median [IQR] | 3.48 [2.76, 4.32] | 3.47 [2.76, 4.27] | 3.52 [2.76, 4.43] | 0.84 |
| PT, s, median [IQR] | 14.50 [13.30, 15.78] | 14.40 [13.20, 15.70] | 14.90 [13.60, 15.90] | 0.07 |
| DD, μg/ml, median [IQR] | 2.72 [1.29, 5.19] | 2.64 [1.21, 4.58] | 2.99 [1.65, 6.26] | 0.04 |
| LDH, U/L, median [IQR] | 201.20 [156.25, 282.08] | 201.20 [159.70, 276.20] | 201.20 [154.40, 286.80] | 0.93 |
| Alb, g/L, median [IQR] | 32.40 [29.20, 34.98] | 32.50 [29.30, 35.50] | 32.10 [28.70, 34.00] | 0.14 |
| Cr, umol/L, median [IQR] | 75.45 [59.70, 103.40] | 75.30 [59.70, 99.30] | 76.90 [59.70, 106.10] | 0.65 |
| NT-pro BNP, pg/ml, median [IQR] | 254.90 [85.50, 754.80] | 254.90 [83.20, 750.00] | 277.60 [93.00, 775.10] | 0.63 |
| Lac, mmol/L, median [IQR] | 1.45 [1.00, 2.40] | 1.50 [1.00, 2.50] | 1.40 [1.00, 2.20] | 0.23 |
| Clinical events | ||||
| Mechanical ventilation, n (%) | 243 (75.5) | 172 (76.4) | 71 (73.2) | 0.63 |
| AKI, n (%) | 44 (13.7) | 31 (13.8) | 13 (13.4) | 1.00 |
| RRT, n (%) | 26 (8.1) | 21 (9.3) | 5 (5.2) | 0.30 |
| Death, n (%) | 13 (4.0) | 10 (4.4) | 3 (3.1) | 0.80 |
| Outcome | ||||
| Plasma levels of Vitamin C, μmol/L, median [IQR] | 17.01 [8.48, 34.33] | 16.93 [8.29, 34.93] | 19.19 [8.94, 30.39] | 0.82 |
| Hypovitaminosis C, n (%) | 201 (62.4) | 140 (62.2) | 61 (62.9) | 1.00 |
| Vitamin C deficiency, n (%) | 110 (34.2) | 76 (33.8) | 34 (35.1) | 0.98 |
NLR neutrophil lymphocyte ratio, CRP C-reactive protein, PCT procalcitonin, Fib fibrinogen, DD D-dimer, PT prothrombin time, LDH lactic dehydrogenase, Alb albumin, Cr creatinine, NT-pro BNP NT-pro brain natriuretic peptide, AKI acute kidney injury, RRT renal replacement therapy.