Table 2 Patient characteristics. Categorical data are expressed as numbers with percentages (%) and were tested using the chi-squared test. Mean and standard deviation (SD) are provided for quantitative variables, and variables were tested using the analysis of variance for before-matching data and the Friedman test for after-matching data. APACHE, Acute Physiology and Chronic Health Evaluation; ER, emergency room; GCS, Glasgow Coma Scale; ICU, intensive care unit; PaO2, partial pressure of arterial oxygen; WBC, white blood cell
| Â | Before matching | After matching | ||||||
|---|---|---|---|---|---|---|---|---|
Period | High-former | Low-mid | High-latter | p-value | High-former | Low-mid | High-latter | p-value |
n | 251 | 213 | 498 | Â | 200 | 200 | 200 | Â |
Predicted mortality (%) | 26.1 (22.4) | 31.7 (23.5) | 30.6 (22.5) | 0.012 | 30.0 (22.6) | 30.0 (22.6) | 30.0 (22.7) | 0.577 |
APACHE II score | 15.3 (8.09) | 17.7 (7.64) | 17.5 (7.32) |  < 0.001 | 16.9 (7.83) | 17.2 (7.47) | 17.5 (7.23) | 0.863 |
Age (years) | 73.3 (15.9) | 74.3 (14.5) | 70.5 (16.7) | 0.006 | 75.2 (14.5) | 74.3 (14.3) | 71.8 (15.4) | 0.127 |
Mean arterial pressure (mmHg) | 88.9 (35.2) | 92.7 (39.6) | 89.2 (42.5) | 0.511 | 87.7 (38.3) | 93.6 (40.1) | 88.2 (43.4) | 0.059 |
Heart rate (beats/min) | 81.1 (23.1) | 83.4 (27.4) | 81.4 (26.5) | 0.562 | 81.7 (24.0) | 83.2 (27.2) | 82.5 (26.4) | 0.870 |
Respiratory rate (breaths/min) | 18.7 (7.71) | 20.7 (9.01) | 20.7 (8.87) | 0.006 | 18.9 (8.12) | 20.5 (8.92) | 21.3 (8.93) | 0.095 |
Temperature (℃) | 36.9 (0.99) | 37.1 (0.93) | 37.1 (0.95) | 0.052 | 36.9 (1.06) | 37.0 (0.94) | 37.1 (0.97) | 0.371 |
GCS score | 12.0 (3.94) | 11.4 (4.30) | 11.1 (4.59) | 0.028 | 11.5 (4.10) | 11.64 (4.13) | 11.4 (4.44) | 0.861 |
Sodium (mmol/L) | 137.8 (4.87) | 139.6 (5.66) | 138.7 (5.17) |  < 0.001 | 137.9 (5.14) | 139.6 (5.57) | 138.9 (5.59) | 0.052 |
Potassium (mmol/L) | 3.81 (0.59) | 3.77 (0.58) | 3.80 (0.59) | 0.739 | 3.82 (0.61) | 3.77 (0.59) | 3.74 (0.53) | 0.541 |
pH | 7.42 (0.08) | 7.42 (0.07) | 7.41 (0.08) | 0.084 | 7.42 (0.08) | 7.42 (0.07) | 7.41 (0.08) | 0.357 |
PaO2 (mmHg) | 83.7 (23.0) | 81.2 (21.9) | 83.4 (17.7) | 0.344 | 81.3 (22.0) | 81.1 (22.25) | 83.4 (18.4) | 0.114 |
WBC count (103/mm3) | 10.1 (5.08) | 10.0 (5.46) | 10.7 (7.16) | 0.318 | 10.4 (5.21) | 9.43 (4.53) | 10.70 (6.40) | 0.349 |
Creatinine (mg/dL) | 1.21 (1.25) | 1.48 (1.93) | 1.46 (2.29) | 0.205 | 1.27 (1.25) | 1.51 (1.98) | 1.55 (3.08) | 0.732 |
Hematocrit (%) | 33.5 (6.21) | 32.7 (6.34) | 33.0 (6.27) | 0.353 | 33.1 (6.20) | 32.9 (6.28) | 32.7 (6.37) | 0.633 |
APACHE II diagnostic category weight | -1.43 (1.51) | -0.96 (1.30) | -1.07 (1.33) |  < 0.001 | -1.07 (1.27) | -1.05 (1.26) | -1.05 (1.26) | 0.130 |
Sex | Â | Â | 0.895 | Â | Â | Â | 0.826 | |
 Female | 106 (42.2) | 88 (41.3) | 215 (43.2) |  | 87 (43.5) | 81 (40.5) | 85 (42.5) |  |
 Male | 145 (57.8) | 125 (58.7) | 283 (56.8) |  | 113 (56.5) | 119 (59.5) | 115 (57.5) |  |
The reason for ICU admission | Â | Â | 0.818 | Â | Â | Â | 0.630 | |
 Emergency surgery | 50 (19.9) | 45 (21.1) | 95 (19.1) |  | 40 (20.0) | 41 (20.5) | 34 (17.0) |  |
 ER or ward | 201 (80.1) | 168 (78.9) | 403 (80.9) |  | 160 (80.0) | 159 (79.5) | 166 (83.0) |  |
Severe organ failure | Â | Â | 0.854 | Â | Â | Â | 0.330 | |
 None | 200 (79.7) | 174 (81.7) | 403 (80.9) |  | 153 (76.5) | 165 (82.5) | 158 (79.0) |  |
 Severe organ failure | 51 (20.3) | 39 (18.3) | 95 (19.1) |  | 47 (23.5) | 35 (17.5) | 42 (21.0) |  |