Patient characteristics
This study enrolled 56 patients who consented to participate. After excluding 8 patients (2 with a disease other than PBC diagnosed by histopathology, and 6 who could not adequately hold their breath during At-PI), 48 patients comprising 8 men and 40 women aged 60 ± 13 years were included in the analysis. Fibrosis stage was 0 in 18 patients, 1 in 18 patients, 2 in 10 patients, and 3 in 2 patients. Clinical, biochemical, and histological characteristics of the patients with PBC (N = 48) analyzed in this study are summarized in Tables 1-4.
Table 1 Clinical and biochemical characteristics of 48 patients with PBC
Variable
|
Value*
|
Sex (M/F)
|
8/40
|
Age (years)
|
61 ± 14
|
AST (U/L)
|
45 ± 21
|
ALT (U/L)
|
43 ± 23
|
Alb (g/dL)
|
3.9 ± 0.4
|
T-Bil (mg/dL)
|
0.7 ± 0.3
|
D-Bil (mg/dL)
|
0.2 ± 0.1
|
ALP (U/L)
|
504 ± 371
|
GGT (U/L)
|
196 ± 182
|
TC (mg/dL)
|
196 ± 44
|
PLT (×104/µL)
|
21.5 ± 7.8
|
PT (%)
|
106 ± 22
|
IgM (mg/dL)
|
351 ± 251
|
FIB-4
|
2.37 ± 7.8
|
AST/ALT ratio
|
1.14 ± 0.38
|
Alb, albumin; ALP, alkaline phosphatase; ALT, alanine aminotransferase; AST, aspartate aminotransferase; D-Bil, direct bilirubin; FIB-4, Fibrosis-4; GGT, γ-glutamyl transferase; IgM, immunoglobin M; PLT, platelet count; PT, prothrombin time; T-Bil, total bilirubin; TC, total cholesterol.
*Values are expressed as the mean ± standard deviation or numbers of patients.
Table 2 Clinical and biochemical characteristics by liver fibrosis stage
Variable
|
F0
|
F1
|
F2-3
|
Sex (M/F)
|
2/16
|
3/15
|
3/9
|
Age (years)
|
52 ± 13
|
63 ± 14*
|
70 ± 6**
|
AST (U/L)
|
39 ± 20
|
41 ± 16
|
62 ± 22*†
|
ALT (U/L)
|
40 ± 19
|
37 ± 14
|
57 ± 34
|
Alb (g/dL)
|
4.0 ± 0.3
|
4.0 ± 0.3
|
3.6 ± 0.5*
|
T-Bil (mg/dL)
|
0.7 ± 0.2
|
0.6 ± 0.1
|
1.0 ± 0.3*‡
|
D-Bil (mg/dL)
|
0.1 ± 0.03
|
0.1 ± 0.02
|
0.3 ± 0.2**‡
|
ALP (U/L)
|
486 ± 266
|
460 ± 247
|
598 ± 608
|
GGT (U/L)
|
154 ± 127
|
175 ± 152
|
288 ± 263
|
TC (mg/dL)
|
207 ± 39
|
188 ± 35
|
192 ± 60
|
PLT (×104/µL)
|
23.5 ± 6.2
|
21.9 ± 9.2
|
17.9 ± 7.1*
|
PT (%)
|
113 ± 26
|
103 ± 16
|
99 ± 24
|
IgM (mg/dL)
|
277 ± 127
|
396 ± 249
|
384 ± 365
|
FIB-4
|
1.53 ± 0.9
|
2.40 ± 1.6
|
3.58 ± 1.2**†
|
AST/ALT ratio
|
1.06 ± 0.45
|
1.16 ± 0.34
|
1.22 ± 0.33
|
Alb, albumin; ALP, alkaline phosphatase; ALT, alanine aminotransferase; AST, aspartate aminotransferase; D-Bil, direct bilirubin; FIB-4, Fibrosis-4; GGT, γ-glutamyl transferase; IgM, immunoglobin M; PLT, platelet count; PT, prothrombin time; T-Bil, total bilirubin; TC, total cholesterol.
Values are expressed as the mean ± standard deviation or numbers of patients.
Significant difference between fibrosis stages were examined by the Kruskal-Wallis test.
* p<0.05 compared to F0. ** p<0.01 compared to F0. †p<0.05 compared to F1. ‡p<0.01 compared to F1.
Table 3 Histological characteristics of 48 patients with PBC
Variable
|
Value
|
Fibrosis stage (F)
|
F0
|
18
|
F1
|
18
|
F2
|
10
|
F3
|
2
|
Bile duct loss (BL)
|
BL0
|
15
|
BL1
|
22
|
BL2
|
8
|
BL3
|
3
|
Cholangitis activity (CA)
|
CA0
|
19
|
CA1
|
8
|
CA2
|
10
|
CA3
|
11
|
Hepatitis activity (HA)
|
HA0
|
23
|
HA1
|
9
|
HA2
|
13
|
HA3
|
3
|
Staging
|
Stage 1
|
9
|
Stage 2
|
27
|
Stage 3
|
10
|
Stage 4
|
2
|
Table 4 Histological characteristics of 48 patients with PBC by liver fibrosis stage
Variable
|
F0
|
F1
|
F2-3
|
Bile duct loss (BL)
|
BL0
|
9
|
3
|
3
|
BL1
|
5
|
12
|
5
|
BL2
|
2
|
3
|
3
|
BL3
|
2
|
0
|
1
|
Cholangitis activity (CA)
|
CA0
|
14
|
2
|
3
|
CA1
|
3
|
4
|
1
|
CA2
|
1
|
4
|
5
|
CA3
|
0
|
8
|
3
|
Hepatitis activity (HA)
|
HA0
|
13
|
6
|
4
|
HA1
|
2
|
6
|
1
|
HA2
|
3
|
6
|
4
|
HA3
|
0
|
0
|
3
|
Staging
|
Stage 1
|
9
|
0
|
0
|
Stage 2
|
7
|
15
|
5
|
Stage 3
|
2
|
3
|
5
|
Stage 4
|
0
|
0
|
2
|
Correlation between At-PI and serological markers
Correlations of ROR with AST, ALT, T-Bil, D-Bil, ALP, GGT, albumin, TC, PLT, IgM, FIB-4, and AST/ALT ratio were examined. ROR was positively correlated with AST (p = 0.004, r = 0.41), D-Bil (p = 0.003, r = 0.429), FIB-4 (p < 0.001, r = 0.53), and AST/ALT ratio (p = 0.032, r = 0.31), and negatively correlated with PLT (p = 0.046, r = -0.29), and ALB (p = 0.002, r = -0.43). ROR was not significantly correlated with ALT, T-Bil, ALP, GGT, TC, prothrombin time (%), or IgM (Table 5).
Table 5 Correlation between ROR on At-PI and serological markers
Parameter
|
ra
|
p
|
AST
|
.411
|
.004
|
ALT
|
.252
|
.084
|
T-Bil
|
.278
|
.055
|
D-Bil
|
.422
|
.003
|
Alb
|
−.435
|
.002
|
ALP
|
.107
|
.469
|
GGT
|
.163
|
.270
|
TC
|
−.200
|
.173
|
PLT
|
−.290
|
.046
|
PT
|
−.252
|
.084
|
IgM
|
.018
|
.906
|
AST/ALT ratio
|
.310
|
.032
|
Fib-4
|
.526
|
<.001
|
Alb, albumin; ALP, alkaline phosphatase; ALT, alanine aminotransferase; AST, aspartate aminotransferase; D-Bil, direct bilirubin; FIB-4, Fibrosis-4; GGT, γ-glutamyl transferase; IgM, immunoglobin M; PLT, platelet count; PT, prothrombin time; ROR, ratio of red; T-Bil, total bilirubin; TC, total cholesterol.
aSpearman’s correlation coefficient.
Correlation between At-PI and SWE
For additional analysis, 27 (4 men, 23 women) of the 48 patients consented to undergo SWE. Mean age was 61 ± 13 (range, 32-78) years. Fibrosis stage was F0 in 11 patients, F1 in 11, F2 in 5, and F3 in 0. ROR range (%) was not correlated with Vs (p = 0.34, r = 0.19).
Multiple comparisons of At-PI from liver pathological factors
Fibrosis stage was F0 in 18, F1 in 18, F2 in 10, and F3 in 2 patients. Bile duct loss score was BL0 in 15, BL1 in 22, BL2 in 8, and BL3 in 3 patients. CA score was CA0 in 19, CA1 in 8, CA2 in 10, and CA3 in 11 patients. HA score was HA0 in 17, HA1 in 13, HA2 in 13, and HA3 in 3 patients. Disease stage was stage 1 in 9, stage 2 in 27, stage 3 in 10, and stage 4 in 2 patients. The Jonckheere-Terpstra test revealed that the ROR significantly increased with increasing fibrosis stage (from F0 to F3, p < 0.01). Multiple comparisons showed significant differences between F0 and F2-F3 (p < 0.01) and F1 and F2-F3 (p < 0.01; Fig. 1a). However, ROR values did not significantly differ by bile duct loss score, CA, HA, or disease stage (Fig. 1b-e).
Multiple comparisons of SWE from liver pathological factors
The Jonckheere-Terpstra test revealed that Vs values increased with the progression of fibrosis stage (from F0 to F3, p < 0.01). Multiple comparisons showed significant differences between F0 and F1 (p < 0.05), F0 and F2-F3 (p < 0.05; Fig. 2a), and HA0 and HA1 (p < 0.05; Fig. 2b). However, Vs values did not significantly differ by bile duct loss score, CA, or disease stage (Fig. 2c-e).
Diagnostic capability of At-PI, SWE, and serum fibrosis markers for fibrosis stage based on ROC curves
Results of the comparison between At-PI, SWE, and serum fibrosis markers in patients with PBC are shown in Table 6.
Table 6 Results of comparison between serum fibrosis markers, SWE, and At-PI in 48 patients with PBC
|
F ≥ 1
|
F ≥ 2
|
Method
|
Sensitivity (%)
|
Specificity (%)
|
AUROC
|
Sensitivity (%)
|
Specificity (%)
|
AUROC
|
AST/ALT ratio
|
0.77
|
0.50
|
0.62
|
0.67
|
0.56
|
0.60
|
FIB-4
|
0.60
|
0.94
|
0.78
|
0.83
|
0.81
|
0.85
|
SWE
|
0.75
|
0.82
|
0.84
|
0.60
|
0.86
|
0.80
|
At-PI
|
0.67
|
0.89
|
0.77
|
0.92
|
0.81
|
0.92
|
At-PI, arrival time parametric imaging; AUROC, area under the receiver operating characteristic curve; FIB-4, Fibrosis-4; SWE, shear wave elastography.
At-PI
The cutoff value and AUROC were respectively 47.1 and 0.92 for diagnosis of fibrosis stage F0-1 and ≥F2-3, and 36.7 and 0.77 for stages F0 and ≥F1-3. When these values were used to diagnose cases of ≥F1 and ≥F2 on At-PI, the sensitivity and specificity were respectively 0.92 and 0.81 for ≥F2 and 0.67 and 0.89 for ≥F1 (Fig. 3a, b).
SWE
The cutoff value and AUROC were respectively 1.40 and 0.80 for diagnosis of fibrosis scores F0-1 and ≥F2-3, and 1.23 and 0.84 for F0 and ≥F1-3. When these values were used to diagnose cases of ≥F1 and ≥F2 on At-PI, the sensitivity and specificity were respectively 0.60 and 0.86 for ≥F2 and 0.75 and 0.82 for ≥F1.
FIB-4
The cutoff value and AUROC were respectively 2.78 and 0.85 for diagnosis of fibrosis scores F0-1 and ≥F2-3, and 2.47 and 0.78 for F0 and ≥F1-3. When these values were used to diagnose cases of ≥F1 and ≥F2 on At-PI, the sensitivity and specificity were respectively 0.83 and 0.81 for ≥F2 and 0.60 and 0.94 for ≥F1.
AST/ALT ratio
The cutoff value and AUROC were respectively 1.05 and 0.60 for diagnosis of fibrosis scores F0-1 and ≥F2-3, and 0.96 and 0.62 for F0 and ≥F1-3. When these values were used to diagnose cases of ≥F1 and ≥F2 on At-PI, the sensitivity and specificity were respectively 0.67 and 0.56 for ≥F2 and 0.77 and 0.50 for ≥F1.
Univariate and multivariate analysis of predictive factors for the progression of liver fibrosis in patients with PBC
Among the four diagnostic tools for fibrosis (AST/ALT ratio, FIB-4, SWE, At-PI) that were evaluated for ability to predict progression of liver fibrosis (liver fibrosis >F2) in patients with PBC, multivariate analysis identified At-PI as an independent factor (Table 7).
Table 7 Predictive factors for liver fibrosis >F2 by univariate and multivariate analysis in patients with PBC
|
Univariate analysis
|
Multivariate analysis
|
Parameter
|
OR (95% CI)
|
p
|
OR (95% CI)
|
p
|
AST/ALT ratio
|
2.02 (0.37-11.05)
|
.418
|
|
|
FIB-4
|
2.21 (1.27-3.84)
|
.005
|
1.76 (0.93-3.32)
|
.083
|
SWE
|
201 (0.76-534)
|
.063
|
|
|
At-PI
|
1.11 (1.04-1.17)
|
<.001
|
1.10 (1.03-1.18)
|
.003
|
At-PI, arrival time parametric imaging; CI, confidence interval; FIB-4, Fibrosis-4; OR, odds ratio; PBC, primary biliary cholangitis; SWE, shear wave elastography.