1.The serum concentration of PK2 in children with Kawasaki disease was significantly decreased.
In order to explore the expression of PK2 in children with Kawasaki disease, ELISA was used to detect the serum concentration of PK2 from 31 healthy children, 21 children with common fever and 70 children with Kawasaki disease. The results were shown in Figure 1. Compared with normal children and children with common fever, the level of PK2 with Kawasaki disease was significantly lower, and the difference was statistically significant.
2.Other laboratory auxiliary indicators in children with Kawasaki disease.
At present, there is no specific diagnostic indicator for Kawasaki disease. Clinicians mainly make comprehensive judgments based on clinical symptoms combined with laboratory indicators. Therefore, we collected and sorted out the common laboratory auxiliary indicators of children with Kawasaki disease. Through the analysis of Kruskal-Wallis test and Mann Whitney U test, results were shown in Figure 2 and Table 1, compared with healthy children and children with common fever, the levels of WBC, PLT, NLR and CRP in children diagnosed as Kawasaki disease were significantly increased, RBC and Hg on the contrary yet, which was consistent with the conclusions reported in the previous literature24 25. Compared with children with common fever, Kawasaki disease children had obviously higher ESR, all the differences were statistically significant. What is different from previous literature reports in our experiment were the days of fever and a common indicator reflecting bacterial infection-PCT, although increased in children with Kawasaki disease, were not significantly statistical difference compared with the results of children with ordinary fever.
Table 1. Clinical characteristics of study population.
Laboratory Metrics
|
NC(n=31)
|
FC(n=20)
|
KD(n=70)
|
p
|
WBC
|
6.1950(1.95)
|
10.2900(8.57)
|
13.5900(7.31)
|
< 0.0001
|
PLT
|
311.5000(77.25)
|
287.5000(223.25)
|
396.0000(169.00)
|
0.0018
|
NLR
|
0.80000(0.75)
|
1.1250(18.25)
|
2.3333(1.67)
|
< 0.0001
|
CRP
|
0.0000(0.00)
|
30.5000(41.75)
|
42.0000(43.00)
|
< 0.0001
|
RBC
|
4.6550(0.40)
|
4.0950(0.36)
|
4.1300(0.54)
|
< 0.0001
|
Hg
|
125.5000(10.25)
|
112.5000(18.25)
|
109.0000(14.00)
|
< 0.0001
|
ESR
|
0.0000(0.00)
|
46.0000(52.25)
|
69.0000(39.50)
|
0.0092
|
PCT
|
0.0000(0.00)
|
0.2050(1.66)
|
0.4600(0.80)
|
0.1592
|
Table 1. Clinical characteristics of study population. Data were presented as median and interquartile range (IQR)with parentheses; P values from Kruskal-Wallis test or Mann-Whitney U test, where appropriate.
3. Correlations between PK2 and patient characteristics.
In the above results, we found that the serum PK2 was significantly decreased in children with Kawasaki disease, suggesting that PK2 may have the potential to be a biomarker in Kawasaki disease. Thus, so as to make a thorough inquiry the function of PK2 in Kawasaki disease, we first conducted a correlation analysis with other existing auxiliary indicators in laboratory. The results were shown in Figure 3. After analyzing the correlation coefficient and P value, we concluded that PK2 was negatively associated with NLR in Kawasaki disease.
To probe the ability of PK2 and other laboratory parameters to distinguish children with Kawasaki disease from children with common fever, ROC curves were used to evaluate their diagnostic performance. The results were shown in Figure 4A, indicating that PK2 performed the best in distinguishing common fever from Kawasaki disease, with an AUC of 0.782. To further demonstrate its predictive power, we plotted Table 2, showing that PK2 was higher than other biomarkers in specificity, positive likelihood ratio and Youden index.
Table2. Predict ability of biomarkers to distinguish Kawasaki disease from common fever.
|
P
|
AUC
|
95% CI
|
Se (%)
|
Sp (%)
|
LR+
|
LR-
|
Youden’s index
|
CRP
|
0.1805
|
0.601
|
0.492 - 0.703
|
50.72
|
75.00
|
2.0288
|
0.6571
|
0.2572
|
ESR
|
0.0120
|
0.697
|
0.582 - 0.796
|
83.87
|
50.00
|
1.6774
|
0.3226
|
0.3387
|
PLT
|
0.0434
|
0.659
|
0.551 - 0.757
|
78.26
|
55.00
|
1.7391
|
0.3953
|
0.3326
|
WBC
|
0.0134
|
0.682
|
0.575 - 0.777
|
92.75
|
40.00
|
1.5458
|
0.1813
|
0.3275
|
NLR
|
0.0026
|
0.735
|
0.631 - 0.823
|
85.51
|
60.00
|
2.1378
|
0.2415
|
0.4551
|
PK2
|
<0.0001
|
0.782
|
0.683 - 0.862
|
71.43
|
80.00
|
3.5715
|
0.3571
|
0.5143
|
PK2+CRP
|
<0.0001
|
0.783
|
0.683-0.863
|
69.57
|
80.00
|
3.4785
|
0.3803
|
0.4957
|
PK2+ESR
|
<0.0001
|
0.827
|
0.724-0.903
|
75.81
|
87.50
|
6.0648
|
0.2765
|
0.6331
|
PK2+WBC
|
<0.0001
|
0.802
|
0.704-0.879
|
56.52
|
95.00
|
11.304
|
0.4577
|
0.5152
|
PK2+NLR
|
<0.0001
|
0.801
|
0.703-0.878
|
69.57
|
85.00
|
4.6380
|
0.3580
|
0.5457
|
PK2+PLT
|
<0.0001
|
0.814
|
0.717-0.888
|
71.01
|
85.00
|
4.734
|
0.3411
|
0.5601
|
PK2+WBC+ESR
|
<0.0001
|
0.826
|
0.723-0.902
|
75.81
|
87.50
|
6.0648
|
0.2765
|
0.6331
|
5. Predictive value of multiple infection biomarker combination scores for Kawasaki disease.
According to the analysis results of the ROC curve in Figure 4A, we tried to further combine the commonly used clinical laboratory biomarkers (WBC, PLT, CRP, ESR and NLR) with PK2. We tested combinations including two and three biomarkers, and the results were shown in Figure 4B and Table 2. The results showed that combining PK2 and WBC increased its AUC value from 0.782 to 0.802, and its specificity increased from 80% to 95%; combining PK2 and ESR increased its AUC value from 0.782 increased to 0.827, and its specificity increased from 80% to 87.50%; when WBC, ESR, and PK2 were combined, the AUC value was adjusted from 0.827 to 0.826, and the specificity did not change significantly. Therefore, combining PK2 with ESR has better early predictive value for Kawasaki disease.
6.Serum expression of PK2 differed in different degrees of coronary artery injury.
Coronary artery injury is the most common and serious complication of Kawasaki disease. Thence, to quest whether the expression level of PK2 in the clinical manifestations of Kawasaki disease is complete and whether there is coronary artery injury, we further divided the Kawasaki disease group into incomplete Kawasaki disease group (Incomplete KD) and complete Kawasaki disease group (Complete KD) according to the latest guideline, as well as Kawasaki disease group without coronary artery injury (The NCAL) and with coronary artery injury (The CAL). Analyzing the ELISA test results, we discovered the results shown in Figure 5. Interestingly, as shown in Figure 5A, compared with the Incomplete KD, the serum PK2 in the Complete KD was lower; compared with the NCAL, PK2 was higher in the CAL shown in Figure 5B. According to the Z value, further analysis that PK2 was different in different severity of coronary injury, showing a positive correlation trend, as shown in Figure 5C.