Patient selection and characteristics
A total of 1190 patients with TBI who met the inclusion criteria were enrolled in this study. After applying the exclusion criteria, 1024 patients were finally included (Fig. 1). The number of male patients was 767 (74.9%), and the median patient age was 63.1 years (52.0–74.0 years). The 48-h mortality rate was 8.7% (n = 89). Of the 89 nonsurvivors, 79 (88.8%) died from brain herniation and 10 (11.25) died from massive hemorrhage.
Comparison of baseline and clinical characteristics between survivors and nonsurvivors
Table 1 compares the characteristics of survivors and nonsurvivors. Nonsurvivors had lower RTS, GCS score, and BT and higher ISS and pulse rate than survivors. No significant difference in SBP was observed between survivors and nonsurvivors. MT was more frequently performed in nonsurvivors than in survivors (Table 1).
Table 1
Comparison of baseline characteristics of patients with TBI according to in-hospital mortality within 48 h
Variables | Patients with TBI (N = 1024) | Survivors (n = 935) | Nonsurvivors (n = 89) | P |
Age, years | 63.1 (52.0–74.0) | 63.1 (52.0–74.0) | 67.0 (53.1–76.5) | 0.072 |
Male sex, n (%) | 767 (74.9) | 700 (74.9) | 67 (75.3) | 1.000 |
Trauma mechanism | | | | 1.000 |
Blunt | 1020 (99.6) | 931 (99.6) | 89 (100.0) | |
Penetrating | 4 (0.4) | 4 (0.4) | 0 (0.0) | |
Revised trauma score | 5.97 (5.03–7.84) | 5.97 (5.64–7.84) | 4.09 (2.83–5.13) | < 0.001 |
Injury severity score | 22 (16–25) | 22 (16–25) | 25 (21–26) | < 0.001 |
Glasgow Coma Scale score | 14 (7–15) | 14 (8–15) | 4 (3–6) | < 0.001 |
Systolic BP, mmHg | 130 (110–140) | 130 (110–140) | 120 (90–160) | 0.259 |
Respiratory rate, /min | 20 (20–20) | 20 (20–20) | 20 (20–24) | 0.002 |
Pulse rate, /min | 84 (74–96) | 84 (74–95) | 92 (73–108) | 0.004 |
Body temperature, ℃ | 36.4 (36.1–36.8) | 36.4 (36.2–36.8) | 36.2 (36.0–36.4) | < 0.001 |
TBI, traumatic brain injury; BP, blood pressure |
A significant difference in PR interval was observed between survivors and nonsurvivors; however, there was no significant difference in the proportion of patients with PR prolongation (Table 2). Moreover, no significant difference was observed in the QRS interval between survivors and nonsurvivors, although the proportion of patients with widened QRS complexes showed a significant difference between groups (Table 1). The QTc interval was more prolonged in nonsurvivors than in survivors (460 [438–480] vs. 479 [456–512] ms, P < 0.001). The incidences of STE and STD in nonsurvivors were higher than those in survivors (Table 2).
Table 2
Comparison of electrocardiogram variables of patients with TBI according to in-hospital mortality within 48 h
Variables | Patients with TBI (N = 1024) | Survivors (n = 935) | Nonsurvivors (n = 89) | P |
PR, ms | 164 (146–184) | 164 (148–186) | 152 (135–174) | 0.001 |
PR prolongation, n (%) | 143 (14) | 134 (14.3) | 9 (10.1) | 0.349 |
QRS, ms | 92 (84–102) | 92 (86–102) | 92 (82–104) | 0.754 |
QRS widening, n (%) | 77 (7.5) | 64 (6.8) | 13 (14.6) | 0.015 |
QTc, ms | 461 (440–482) | 460 (438–480) | 479 (456–512) | < 0.001 |
QTc prolongation, n (%) | 288 (28.1) | 245 (26.2) | 43 (48.3) | < 0.001 |
Presence of STE, n (%) | 84 (8.2) | 71 (7.6) | 13 (14.6) | 0.036 |
Presence of STD, n (%) | 158 (15.4) | 108 (11.6) | 50 (56.2) | < 0.001 |
TBI, traumatic brain injury; BP, blood pressure; STE, ST-segment elevation; STD, ST-segment depression |
In the isolated TBI group, survivors had higher RTS, GCS score, and BT values and lower ISS and PR values than non-survivors (Table 3). The PR interval, QTc interval, and incidence rates of QTP and STD were significantly different between survivors and nonsurvivors (Table 4).
Table 3
Comparison of baseline characteristics according to in-hospital mortality within 48 h between the isolated TBI and combined TBI groups
Variables | Isolated TBI (N = 776) | | Combined TBI (N = 248) |
Survivors (n = 715) | Non-survivors (n = 61) | P | | Survivors (n = 220) | Non-survivors (n = 28) | P |
Age, years | 64 (53–74) | 68 (55–77) | 0.138 | | 60 (50–70) | 64 (52–77) | 0.212 |
Male sex, n (%) | 536 (75.0) | 44 (72.1) | 0.737 | | 164 (74.5) | 23 (82.1) | 0.518 |
Preexisting illness, n (%) | | | | | | | |
Previous PCI history | 41 (5.7) | 1 (1.6) | 0.288 | | 5 (2.3) | 1 (3.6) | 1.000 |
Hypertension | 264 (36.9) | 15 (24.6) | 0.074 | | 59 (26.8) | 7 (25.0) | 1.000 |
Diabetes | 164 (22.9) | 12 (19.7) | 0.671 | | 43 (19.5) | 2 (7.1) | 0.179 |
Renal impairment | 13 (1.8) | 0 (0.0) | 0.588 | | 2 (0.9) | 0 (0.0) | 1.000 |
Cerebrovascular accident | 12 (1.7) | 0 (0.0) | 0.632 | | 2 (0.9) | 0 (0.0) | 1.000 |
Trauma mechanism | | | 1.000 | | | | 1.000 |
Blunt | 712 (99.6) | 61 (100.0) | | | 219 (99.5) | 28 (100.0) | |
Penetrating | 3 (0.4) | 0 (0.0) | | | 1 (0.5) | 0 (0.0) | |
Revised trauma score | 5.97 (5.64–7.84) | 4.09 (2.83–5.97) | < 0.001 | | 5.97 (5.08–7.84) | 4.09 (2.63–5.03) | < 0.001 |
Injury severity score | 17 (16–25) | 25 (20–25) | < 0.001 | | 26 (22–34) | 29 (23–38) | 0.066 |
Glasgow Coma Scale score | 14 (8–15) | 4 (3–6) | < 0.001 | | 15 (8–15) | 3 (3–7) | < 0.001 |
Systolic BP, mmHg | 130 (110–150) | 140 (105–160) | 0.232 | | 110 (100–130) | 85 (70–110) | < 0.001 |
Respiratory rate, /min | 20 (20–20) | 20 (20–22) | 0.229 | | 20 (20–22) | 22 (20–24) | 0.002 |
Pulse rate, /min | 82 (72–92) | 90 (72–105) | 0.022 | | 90 (80–104) | 97 (80–110) | 0.244 |
Body temperature, ℃ | 36.4 (36.2–36.8) | 36.2 (36.0–36.5) | < 0.001 | | 36.4 (36.0–36.8) | 36.2 (36.0–36.3) | 0.003 |
Massive transfusion, n (%) | 33 (4.6) | 7 (11.5) | 0.043 | | 31 (14.1) | 14 (50.0) | < 0.001 |
Emergency operation, n (%) | 206 (28.8) | 10 (16.4) | 0.054 | | 37 (16.8) | 6 (21.4) | 0.732 |
TBI, traumatic brain injury; BP, blood pressure |
Table 4
Comparison of electrocardiogram variables according to in-hospital mortality within 48 h between the isolated TBI and combined TBI groups
Variables | Isolated TBI (N = 776) | | Combined TBI (N = 248) |
Survivors (n = 715) | Non-survivors (n = 61) | P | | Survivors (n = 220) | Non-survivors (n = 28) | P |
PR, ms | 166 (152–188) | 162 (138–176) | 0.010 | | 152 (136–172) | 138 (132–172) | 0.080 |
PR prolongation, n (%) | 114 (15.9) | 8 (13.1) | 0.690 | | 20 (9.1) | 1 (3.6) | 0.530 |
QRS, ms | 92 (86–102) | 92 (82–102) | 0.342 | | 89 (82–100) | 91 (83–117) | 0.272 |
QRS widening, n (%) | 50 (7.0) | 7 (11.5) | 0.302 | | 14 (6.4) | 6 (21.4) | 0.017 |
QTc, ms | 458 (438–480) | 476 (454–513) | < 0.001 | | 462 (444–482) | 484 (466–511) | 0.002 |
QTc prolongation, n (%) | 180 (25.2) | 28 (45.9) | < 0.001 | | 65 (29.5) | 15 (53.6) | 0.019 |
Presence of STE, n (%) | 55 (7.7) | 9 (14.8) | 0.093 | | 16 (7.3) | 4 (14.3) | 0.360 |
Presence of STD, n (%) | 85 (11.9) | 30 (49.2) | < 0.001 | | 23 (10.5) | 20 (71.4) | < 0.001 |
TBI, traumatic brain injury; STE, ST-segment elevation; STD, ST-segment depression |
In the combined TBI group, survivors had higher RTS, GCS score, SBP, and BT values and lower RR value than non-survivors (Table 3). The QTc interval and incidence rates of QRS widening, QTP, and STD were significantly different between survivors and nonsurvivors (Table 4).
Multivariate analysis for predicting 48-h mortality in patients with TBI
After adjusting for confounding factors, RTS (OR, 0.561; 95% CI, 0.483–0.650), BT (OR, 0.627; 95% CI, 0.413–0.953), emergency operation (OR, 0.363; 95% CI, 0.191–0.688), QTP (OR, 2.017; 95% CI, 1.203–3.382), and STD (OR, 8.428; 95% CI, 5.019–14.152) were independently associated with 48-h mortality in patients with TBI (Table 5).
Table 5
Multivariate logistic regression analysis for predicting in-hospital mortality in patients with TBI
Variables | Adjusted OR (95% CI) | P |
Age, years | 1.012 (0.996–1.029) | 0.133 |
Revised trauma score | 0.585 (0.507–0.674) | < 0.001 |
Injury severity score | 1.016 (0.980–1.054) | 0.389 |
Pulse rate, /min | 1.008 (0.996–1.020) | 0.193 |
Body temperature, ℃ | 0.610 (0.404–0.920) | 0.018 |
ECG variables | | |
PR prolongation | 0.671 (0.298–1.511) | 0.335 |
QRS complex widening | 1.486 (0.684–3.228) | 0.317 |
QTc prolongation | 1.934 (1.164–3.214) | 0.011 |
Presence of STE | 1.140 (0.509–2.552) | 0.749 |
Presence of STD | 8.387 (5.038–13.962) | < 0.001 |
TBI, traumatic brain injury; OR, odds ratio; CI, confidence interval; STE, ST-segment elevation; STD, ST-segment depression |
In the isolated TBI group, QTP (OR, 2.098; 95% CI, 1.111–3.962) and STD (OR, 5.903; 95% CI, 3.146–11.076) were independently associated with 48-h mortality. In the combined TBI group, QTP (OR, 2.837; 95% CI, 1.011–7.958) and STD (OR, 15.430; 95% CI, 5.528–43.067) were associated with 48-h mortality (Table 6).
Table 6
Multivariate logistic regression analysis for predicting in-hospital mortality within 48 h between the isolated TBI and combined TBI groups
| Isolated TBI group | | Combined TBI group |
| Adjusted OR (95% CI) | p | | Adjusted OR (95% CI) | p |
Age, years | 1.010 (0.989–1.031) | 0.349 | | | |
Hypertension | 0.509 (0.251–1.030) | 0.060 | | | |
Diabetes | | | | 0.394 (0.057–2.720) | 0.345 |
Revised trauma score | 0.563 (0.473–0.669) | < 0.001 | | 0.586 (0.422–0.814) | < 0.001 |
Injury severity score | 1.076 (1.005–1.152) | 0.035 | | 0.963 (0.899–1.031) | 0.279 |
Pulse rate, /min | 1.012 (0.996–1.027) | 0.132 | | | |
Body temperature, ℃ | 0.710 (0.435–1.158) | 0.170 | | 0.555 (0.213–1.447) | 0.229 |
Massive transfusion, n (%) | 1.364 (0.434–4.285) | 0.596 | | 2.484 (0.850–7.256) | 0.096 |
Emergency operation | 0.200 (0.089–0.448) | < 0.001 | | | |
ECG variables | | | | | |
PR prolongation | 0.648 (0.262–1.604) | 0.348 | | 1.618 (0.159–16.487) | 0.684 |
QRS complex widening | 1.553 (0.564–4.276) | 0.394 | | 1.666 (0.346–8.008) | 0.524 |
QTc prolongation | 2.098 (1.111–3.962) | 0.022 | | 2.837 (1.011–7.958) | 0.048 |
Presence of STE | 1.642 (0.605–4.461) | 0.330 | | 0.278 (0.052–1.473) | 0.132 |
Presence of STD | 5.903 (3.146–11.076) | < 0.001 | | 15.430 (5.528–43.067) | < 0.001 |
TBI, traumatic brain injury; OR, odds ratio; CI, confidence interval; ECG, electrocardiogram; STE, ST-segment elevation; STD, ST-segment depression |
Prognostic performance of ECG variables for 48-h mortality in patients with TBI
On the basis of multivariate analysis, we set a limit to 48-h mortality in patients with TBI. The presence of STD (4 points) and/or QTP (1 point) was considered to predict 48-h mortality in patients with TBI. When QTP and STD were combined, the sum of scores ranged from 0 to 5, in which a higher score indicated a higher likelihood of 48-h mortality. The AUCs of RTS, ISS, QTP, STD, and the combination of QTP and STD were 0.790 (95% CI, 0.764–0.815), 0.632 (95% CI, 0.602–0.662), 0.605 (95% CI, 0.574–0.635), 0.723 (95% CI, 0.695–0.750), and 0.786 (95% CI, 0.759–0.811), respectively (Fig. 2). The AUC of the combination of QTP and STD was significantly different from that of ISS, STD, and QTP, but not RTS.