Patient characteristics
Table 1 presents the patient characteristics.
Table 1. Patient characteristics
|
|
Survivor
|
Non-survivor
|
p-value*
|
|
n = 82
|
n = 22
|
Demographics
|
|
|
|
Age (years), median (IQR)
|
66 (56 to 76)
|
70 (62 to 79)
|
0.16
|
Male, n (%)
|
49 (60)
|
14 (64)
|
0.74
|
Underlying disease types
|
|
|
|
Hematopoietic disorders, n (%)
|
38 (46)
|
12 (55)
|
0.49
|
Infectious, n (%)
|
36 (44)
|
5 (23)
|
0.07
|
The others, n (%)
|
8 (10)
|
5 (23)
|
0.10
|
Laboratory tests
|
|
|
|
Platelet (×109/L), median (IQR)
|
40 (22 to 60)
|
18.5 (12 to 40)
|
0.03
|
D-dimer (µg/mL), median (IQR)
|
16.3 (9.6 to 43.2)
|
16.2 (11 to 111.2)
|
0.27
|
PT-INR, median (IQR)
|
1.40 (1.13 to 1.55)
|
1.47 (1.27 to 1.70)
|
0.22
|
Fibrinogen (g/L), median (IQR)
|
2.9 (1.2 to 4.1)
|
1.6 (1.2 to 3.0)
|
0.12
|
HMGB1† (ng/mL), median (IQR)
|
6.8 (3.1 to 13.6)
|
16.3 (8.5 to 66.9)
|
<0.001
|
Histone H3† (ng/mL), median (IQR)
|
2.1 (0.4 to 7.8)
|
4.8 (2.4 to 31.6)
|
0.002
|
DIC score (point), median (IQR)
|
5 (5 to 6)
|
5 (5 to 6)
|
0.40
|
5 points, n (%)
|
57 (70)
|
13 (59)
|
0.35
|
6 points, n (%)
|
18 (22)
|
7 (32)
|
0.34
|
7 points, n (%)
|
7 (9)
|
2 (9)
|
0.93
|
8 points, n (%)
|
NA
|
NA
|
NA
|
Anti-DIC agents
|
|
|
|
rhTM, n (%)
|
50 (61)
|
18 (82)
|
0.07
|
Antithrombin, n (%)
|
18 (22)
|
8 (36)
|
0.17
|
PT-INR, prothrombin time-international normalized ratio; HMGB1, high mobility group box-1 protein; DIC, disseminated intravascular coagulation; rhTM, recombinant human soluble thrombomodulin; IQR, interquartile range; NA, not applicable
*p-value is the hypothesis that the proportion or median of the two groups between survivors and non-survivors is the same.
†HMGB1 and histone H3 data were missing for the same patient.
In total, 104 patients from seven hospitals were eligible for this study. Among the 104 patients, 22 (21%) died. Only one patient had missing information on HMGB1 and histone H3. Mortality did not differ among the ISTH DIC scores of 5, 6, and 7 points. No differences were observed in the use of anti-DIC agents. The underlying diseases were summarized in Supplementary Table S3 ( Additional file 3).
Association between mortality and DIC score, serum HMGB1, and histone H3 levels
The 28-day mortality rates at 5, 6, and 7 points were 19% (13/70), 28% (7/25), and 22% (2/9), respectively. The odds ratio for mortality was 1.28 (95% CI: 0.64 to 2.57, p = 0.48) per 1 point rise in the DIC score. The association between serum HMGB1 and histone H3 levels and mortality was almost linear in the logit model as shown in Supplementary Fig. S1 (Additional file 4). The odds ratio for mortality was 1.02 (95% CI: 1.00 to 1.03, p = 0.02) per 1 ng/mL rise in serum HMGB1 levels and 1.02 (95% CI: 1.00 to 1.04, p = 0.04) per 1 ng/mL rise in serum histone H3 levels.
ROC curve showed that 6 points in the DIC score, 8 ng/mL in the serum HMGB1 level, and 2 ng/mL in the serum histone H3 level were the optimal cutoff points. The odds ratios of the DIC score, serum HMGB1, and histone H3 levels as dichotomized variables with the optimal cutoff points were 1.58 (95% CI: 0.60 to 4.17, P = 0.36), 5.47 (95% CI: 1.70 to 17.6, p = 0.004), and 9.07 (95% CI: 2.00 to 41.3, p = 0.004), respectively. Table 2 summarizes the associations between mortality and DIC scores, serum HMGB1, and histone H3 levels.
Table 2. Association between mortality and DIC scores, HMGB1, and histone H3
|
Variables
|
Odds ratio (95% CI)
|
p-value*
|
DIC score (point)
|
1.28 (0.64 to 2.57)
|
0.48
|
HMGB1 (ng/mL)
|
1.02 (1.00 to 1.03)
|
0.02
|
Histone H3 (ng/mL)
|
1.02 (1.00 to 1.04)
|
0.04
|
Optimal cutoff point
|
|
|
DIC score ≥ 6 point
|
1.58 (0.60 to 4.17)
|
0.36
|
HMGB1 ≥ 8 (ng/mL)
|
5.47 (1.70 to 17.6)
|
0.004
|
Histone H3 ≥ 2 (ng/mL)
|
9.07 (2.00 to 41.3)
|
0.004
|
DIC, disseminated intravascular coagulation; HMGB1, high mobility group box-1 protein
* p-value is the null hypothesis that the odds ratio is equal to one.
Comparison of prediction abilities for mortality between DIC score vs. HMGB1 and histone H3
Table 3 shows the prognostic predictive abilities of the DIC scores and serum HMGB1 and histone H3 levels.
Table 3. Comparison of discrimination, calibration, and NRI between DIC scores vs. HMGB1 and histone H3
|
|
DIC scores
|
HMGB1
|
p-value*
|
Histone H3
|
p-value*
|
Discrimination
|
|
|
|
|
|
AUC, (95% CI)
|
0.55
(0.43 to 0.67)
|
0.74
(0.63 to 0.85)
|
0.03
|
0.71
(0.60 to 0.82)
|
0.07
|
Calibration
|
|
|
|
|
|
HL test, P-value
|
0.93
|
0.49
|
NA
|
0.10
|
NA
|
Category-free NRI
|
|
|
|
|
|
Overall NRI, (95% CI)
|
|
0.45
(0.01 to 0.90)
|
0.04
|
0.37
(−0.05 to 0.78)
|
0.08
|
Event NRI
|
|
−0.18
|
|
−0.36
|
|
Non-event NRI
|
|
0.63
|
|
0.73
|
|
DIC, disseminated intravascular coagulation; HMGB1, high mobility group box-1 protein; AUC, area under the receiver operating characteristic curve; HL, Hosmer–Lemeshow; NRI, net reclassification improvement; NA, not applicable.
* p-value is the null hypothesis that each prediction index of the DIC scoring system is equal to that of HMG1 and histone H3.
The AUC of the DIC scores, serum HMGB1, and histone H3 levels was 0.55 (95% CI: 0.43 to 0.67), 0.74 (95% CI: 0.63 to 0.85), 0.71 (95% CI: 0.60 to 0.82), respectively (Supplementary Fig. S2; Additional file 5). The differences in the AUC between serum HMGB1 levels and the DIC scores and serum histone H3 levels and the DIC scores were 0.19 (p = 0.03) and 0. 16 (p = 0.07), respectively.
The p-values in the HL test for the DIC scores, serum HMGB1, and histone H3 levels were 0.93, 0.49, and 0.10, respectively. The DIC scores had a good calibration plot in the range of approximately 20%, and serum HMGB1 levels were in the range of approximately 45% (Fig. 1a, b). The serum histone H3 levels did not show a good calibration plot (Fig. 1c).
The overall category-free NRI by serum HMGB1 levels against the DIC score was 0.45 (95% CI: 0.01 to 0.90, p = 0.04). The overall category-free NRI by serum histone H3 levels against the DIC score was 0.37 (95% CI: −0.05 to 0.78, p = 0.08). The event-and non-event-category-free NRIs are listed in Table 3. Fig. 2 shows the category-free reclassification plot between the predicted probability of DIC scores and that of serum HMGB1 and histone H3 levels. The overall category additive NRI by serum HMGB1 levels at the cutoff point of 8 ng/mL vs. DIC score at the cutoff point of 6 points was 26 (95% CI: −14 to 67, p = 0.10), and absolute NRI was −3% (Supplementary Table S4; Additional file 6). The overall category additive NRI by serum histone H3 levels at the cutoff point of 2 ng/mL vs. DIC score at the cutoff point of 6 points was 28 (95% CI: −19 to 66, p = 0.07), and absolute NRI was −7% (Supplementary Table S5; Additional file 7).