2.1 Year and gender distributions of 876 children with PTB
2.1.1 The composition of 876 cases of PTB in children
A total of 876 children with PTB were enrolled in the study. There were a total of 454 cases in the group with combined extrapulmonary tuberculosis, the percentage was 51.83%, including tuberculous meningitis, abdominal tuberculosis (intestinal tuberculosis, liver tuberculosis, kidney tuberculosis, etc.), bone and joint tuberculosis, spinal tuberculosis, urinary system tuberculosis, lymph node tuberculosis, etc. There were a total of 422 cases in the pulmonary tuberculosis group, the percentage was 48.17%, including 230 cases of simple pulmonary tuberculosis, 150 cases of concurrent tuberculous pleurisy, 41 cases of concurrent tracheal and bronchial tuberculosis, and 1 case of concurrent tuberculous pleurisy and bronchial endometrial tuberculosis. .The results indicated that pulmonary tuberculosis in children were more common in involving other organs outside the lungs, even in in the pulmonary tuberculosis group, lesions involving the bronchial lining and pleura were also common.Figure1a & Figure1b.
2.1.2 Distribution of gender and place of residence of 876 cases of PTB in children
The length of hospitalization ranged from 1 to 124 days, with a median length of 12 days and a inter-quartile range of 8 to 18 days. Among them, there were 150/876 cases (17.12%) in 2016, 169/876 cases (19.29%) in 2017, 186/876 cases (21.23%) in 2018, 177/876 cases (20.21%) in 2019, and 194/876 cases (22.15%) in 2020. There were 479/876 males (54.68%) and 397/876 females (45.32%), with a male to female ratio of 1.21:1. There were trends of increasing number of total and female pediatric patients year by year. Among the 876 children, there were 431 cases (49.20%) in urban areas and 445 cases (50.80%) in rural areas, slightly more cases in rural areas than in cities. Table 1 and Figure 2.
Table1 Distribution of gender and place of residence in PTB from 2016 to 2020
Distribution of sex and place [n(%)]
|
Year
|
male
|
female
|
city
|
countryside
|
2016
|
81(54.00)
|
69(45.00)
|
65(46.33)
|
85(56.67)
|
2017
|
103(60.95)
|
66(39.05)
|
72(42.60)
|
97(57.40)
|
2018
|
107(57.53)
|
79(42.47)
|
97(52.15)
|
89(47.85)
|
2019
|
93(52.54)
|
84(47.46)
|
90(50.85)
|
87(49.15)
|
2020
|
95(48.97)
|
99(51.03)
|
107(55.15)
|
87(44.85)
|
Total
|
479(54.68)
|
397(45.32)
|
431(49.20)
|
445(50.80)
|
2.2 Age distribution of 876 children cases with PTB
Among the 876 children with PTB, there were 54 cases aged 0-6 months, accounting for 6.16%, 44 cases aged 6-12 months, accounting for 5.02%, 96 cases aged 1-3 years, accounting for 10.96%, 172 cases aged 4-7 years, accounting for 19.63%, 262 cases aged 8-12 years, accounting for 29.91%, 206 cases aged 13-15 years, accounting for 23.52%, and 42 cases aged 16-18 years, accounting for 4.79%. There were 682 cases aged three and above, accounting for 77.85%. The results showed that among the 876 cases of PTB in children, children over 3 years old had the most cases, with the main age range of 7-12 years old being 262 cases, followed by 12-15 years old with 206 cases. The distribution differences among different age groups were statistically significant (P<0.05).
Table2. Distribution of children with PTB in different age groups from 2016 to 2020[n(%)
age
|
2016
|
2017
|
2018
|
2019
|
2020
|
χ 2
|
P
|
0~6months
|
12(8.00)
|
12(7.10)
|
9(4.84)
|
8(4.52)
|
13(6.70)
|
43.928
|
0.008
|
~12months
|
7(4.67)
|
14(8.28)
|
9(4.84)
|
11(6.21)
|
3(1.55)
|
|
|
~3years
|
25(16.67)
|
18(10.65)
|
18(9.68)
|
20(11.30)
|
15(7.73)
|
|
|
~7years
|
34(22.67)
|
32(18.93)
|
3(20.97)
|
40(22.60)
|
2(13.92)
|
|
|
~12years
|
41(27.33)
|
50(29.59)
|
57(30.65)
|
58(32.77)
|
56(28.87)
|
|
|
~15years
|
22(14.67)
|
37(21.89)
|
45(24.19)
|
35(19.77)
|
67(35.54)
|
|
|
~18years
|
9(6.00)
|
6(3.55)
|
9(4.84)
|
5(2.82)
|
13(6.70)
|
|
|
2.3 Tuberculosis contact history
Among 876 PTB children, there were 285 (32.53%) cases with clear histories of tuberculosis exposure, and 523 (59.70%) cases denied having histories of tuberculosis exposure, and 68 cases (7.76%) of children had unclear histories of tuberculosis exposure. There was a statistically significant difference in the history of tuberculosis exposure among PTB children of different age groups (P<0.05), with a higher proportion of children under 7 years old having a history of tuberculosis exposure, especially in the 0-1 year old age group. Figure4 & Table3.
Table3 Contact history of tuberculosis in children with PTB of different ages[n(%)]
Age(years)
|
Had history of contact with TB
|
No history of contact with TB
|
χ2
|
P
|
0~1
|
55(59.14)
|
38(40.86)
|
36.669
|
<0.001
|
1~3
|
32(36.36)
|
56(63.64)
|
|
|
3~7
|
67(41.36)
|
95(58.64)
|
|
|
7~12
|
73(29.67)
|
173(70.33)
|
|
|
12~15
|
48(26.37)
|
134(73.63)
|
|
|
15~18
|
10(27.03)
|
27(72.97)
|
|
|
2.4 History of BCG vaccination
Among the 876 children with PTB, 768 (87.67%) cases had history of BCG vaccination, 59 (6.74%) cases had no vaccination history, and 49 (5.59%) cases had unknown vaccination history. Using multiple sample chi square test, Fisher's exact probability analysis for the history of BCG vaccination in various years, the BCG vaccination rate difference was statistically significant (c2=16.689, P=0.034), the results showed that the showed an increasing trend from 2016 to 2020. Table4.
Table4 History of BCG vaccination in children with PTB from 2016 to 2020
Year
|
BCG vaccination(n/%)
|
No BCG vaccination (n/%)
|
Unknown (n/%)
|
2016
|
120 (80.00)
|
18(12.00)
|
12(8.00)
|
2017
|
147(86.98)
|
12(7.10)
|
10(5.92)
|
2018
|
163(87.63)
|
14(7.53)
|
9(4.84)
|
2019
|
165(93.22)
|
7(3.95)
|
5(2.82)
|
2020
|
173(89.18)
|
8(4.12)
|
13(6.70)
|
Total
|
768(87.67)
|
59(6.74)
|
49(5.59)
|
χ2
|
16.689
|
|
|
P
|
0.034
|
|
|
2.5 Comparison between severe tuberculosis group and non severe tuberculosis group
2.5.1 Comparison of General Information
In the severe PTB group, 33.63% of cases were under 3 years old, 60.47% lived in rural areas, and the average length of hospital stay was 16 days, both of which were significantly higher than those in the non severe group, while the BCG vaccination rate (82.01%) was lower than that of the non severe group (91.25%), and the difference was statistically significant (P<0.05). There were no significant differences between the two groups in gender, nationality and tuberculosis exposure history (P>0.05). Although there was no statistically significant difference between the severe and non severe groups in different years, the overall severity rate of children with PTB showed a downward trend.Table5.
Table5 Comparison of tuberculosis general data between the two groups
Category
|
Severe group [n(%)]
|
Non severe group[n(%)]
|
total
|
χ 2
|
P
|
Gender
|
|
|
|
0.071
|
0.79
|
male
|
183(53.98)
|
296(55.12)
|
479(54.68)
|
|
|
female
|
156(46.02)
|
241(44.08)
|
397(45.32)
|
|
|
age
|
|
|
|
59.537
|
<0.001
|
0~6months
|
46(13.57)
|
8(1.49)
|
53(6.16)
|
|
|
~12months
|
23(6.78)
|
21(3.91)
|
45(5.02)
|
|
|
~3years
|
45(13.27)
|
51(9.50)
|
96(10.96)
|
|
|
~7years
|
54(15.93)
|
118(21.97)
|
171(19.63)
|
|
|
~12years
|
82(24.19)
|
180(33.52)
|
261(29.91)
|
|
|
~15years
|
69(20.35)
|
137(25.51)
|
207(23.52)
|
|
|
~18years
|
20(5.90)
|
22(4.10)
|
43(4.79)
|
|
|
Residence
|
|
|
|
20.702
|
<0.001
|
city
|
134(39.53)
|
297(55.31)
|
430(49.20)
|
|
|
countryside
|
205(60.47)
|
240(44.69)
|
446(50.80)
|
|
|
Nation
|
|
|
|
1.039
|
0.308
|
Han Chinese
|
294(86.73)
|
478(89.01)
|
771(88.13)
|
|
|
national minority
|
45(13.27)
|
59(10.99)
|
105(11.87)
|
|
|
Tuberculosis exposure history
|
|
|
|
0.15
|
0.699
|
Had or suspicious
|
125(36.87)
|
205(38.18)
|
334(37.67)
|
|
|
None or unknown
|
214(63.13)
|
332(61.82)
|
542(62.33)
|
|
|
BCG vaccination history
|
|
|
|
16.421
|
<0.001
|
Had
|
278(82.01)
|
490(91.25)
|
767(87.67)
|
|
No or unknown
|
61(17.99)
|
47(8.75)
|
109(12.33)
|
|
|
Admission year
|
|
|
|
9.041
|
0.060
|
2016
|
68(20.06)
|
82(15.27)
|
150(17.12)
|
|
|
2017
|
75(22.12)
|
94(17.50)
|
169(19.29)
|
|
|
2018
|
71(20.94)
|
115(21.42)
|
186(21.23)
|
|
|
2019
|
59(17.40)
|
118(21.97)
|
177(20.21)
|
|
|
2020
|
66(19.47)
|
128(23.84)
|
194(22.15)
|
|
|
2016~2018
|
214(63.12)
|
291(54.19)
|
505(57.65)
|
6.798
|
0.009
|
2019~2020
|
125(36.87)
|
246(45.81)
|
371(42.35)
|
|
|
Hospitalization time[M(P25-P75)]/days
|
16(10~26)
|
10(7~14)
|
12(8-18)
|
-
|
|
2.5.2 Analysis of risk factors for children with severe children cases with PTB
The above factors with significant differences (age, residence, BCG vaccination history) were analyzed by multi-factors binary logistic regression analysis, and the assigned values were shown in Table6. The results showed that non BCG vaccination or unknown vaccination history, age<3 years, and living in rural areas were independent risk factors for children with severe PTB (P<0.05)Figure5.
Table6 Risk factors assignment of severe PTB in children.
Factors
|
Assignment Description
|
Age
|
0=<3岁,1=≥3years old
|
Residence
|
0=Countryside,1=City
|
BCG vaccination history
|
0=Received BCG vaccine or unknown vaccination history,1=BCG vaccination
|