3.1 Patient characteristics
The children were enrolled from 13 hospitals (Table 1). Hospitals are at different levels. There are five county level hospitals, seven city level hospitals and one provincial level hospital.
There were 1560 patients enrolled. There were 132 children were excluded because of incomplete results or information or other reasons. A total of 1428 children completed the study. The ages of the patients ranged from 34 days to 13.9 years with a median 4.3 years (Fig 1). The number of boys was 801 (56.1%).
Table 1 Patients from different hospitals
Hospital
|
Number of patients
|
Ningbo Women and Children's Hospital
|
181
|
Sanmen People's Hospital
|
174
|
Shaoxing Second Hospital
|
171
|
Changxing Maternity and Child Health Care Hospital
|
165
|
Ningbo Medical Center Lihuili Hospital
|
164
|
Taizhou Hospital of Zhejiang Province
|
144
|
The Children’s Hospital, Zhejiang University School of Medicine
|
127
|
Zhoushan Women and Children Hospital
|
83
|
Cixi Maternity and Child Health Care Hospital
|
57
|
Quzhou Maternal and Child Health Care Hospital
|
47
|
Huzhou Central Hospital
|
45
|
The Second Affiliated Hospital of Jiaxing University
|
41
|
Shengsi People's Hospital
|
29
|
3.2 Comparison of M. pneumoniae -DNA positive and negative patients
The positive rate of M. pneumoniae -DNA was 37.4% (534/1428). Positive rate of M. pneumoniae were different in different hospitals (Fig 2). Gender proportion had no significant difference between the groups (boys 55.6% vs. 56.4%, χ2=0.078,p=0.780).
The number of M. pneumoniae -DNA positive and negative patients was 534 (37.4%) and 894 (62.6%). The median ages of M. pneumoniae -DNA positive and negative patients were 5.2 and 3.8 years, respectively, with significant difference between the two groups (p<0.001).
Despite we enrolled patients with fever durations between 2 and 5 days, the fever and cough duration on the first visit had significant difference between M. pneumoniae -DNA positive and negative patients (both p<0.001, Table 2). The proportion of other symptoms, including wheezing, tachypnea, pharyngalgia, chest pain, headache, hoarseness, convulsion, abdominal pain and rash had no significant differences between M. pneumoniae -DNA positive and negative patients (all p >0.05).
In laboratory test, LDH, CRP and neutrophil percentage in M. pneumoniae -DNA positive patients were higher than in M. pneumoniae -DNA negative ones. WBC and lymphocyte percentage were lower in M. pneumoniae -DNA positive patients than in M. pneumoniae -DNA negative ones. Other parameters were also listed in Table 2.
Table 2 Comparison of laboratory test between M. pneumoniae -DNA positive and negative patients
|
M. pneumoniae -DNA positive (n=534)
|
M. pneumoniae -DNA negative (n=894)
|
p
|
Gender (boy/girl, n)
|
297/237
|
504/390
|
0.780
|
Age [median (25th-75th interquartile range), years old, 1428 valid data]
|
5.2 (3.3-7.0)
|
3.8 (2.2-5.7)
|
0.000
|
Symptoms
|
|
|
|
Fever [median (25th-75th interquartile range), day, 1428 valid data]
|
4 (3-4)
|
3 (2-4)
|
0.000
|
Cough [median (25th-75th interquartile range), day, 1428 valid data]
|
3 (2-5)
|
2 (0-4)
|
0.000
|
Wheeze [median (25th-75th interquartile range), day, 1428 valid data]
|
0 (0-0)
|
0 (0-0)
|
0.220
|
Tachypnea [n (%), 1428 valid data]
|
2 (0.4%)
|
4 (0.4%)
|
0.598
|
Pharyngalgia [n (%), 1428 valid data]
|
1 (0.2%)
|
6 (0.7%)
|
0.195
|
Chest pain [n (%), 1428 valid data]
|
0 (0%)
|
1 (0.1%)
|
0.626
|
Headache [n (%), 1428 valid data]
|
0 (0%)
|
2 (0.2%)
|
0.392
|
Hoarseness [n (%), 1428 valid data]
|
3 (0.6%)
|
8 (0.9%)
|
0.360
|
Convulsion [n (%), 1428 valid data]
|
0 (0%)
|
2 (0.2%)
|
0.392
|
Abdominal pain [n (%), 1428 valid data]
|
0 (0%)
|
1 (0.1%)
|
0.626
|
Rash [n (%), 1428 valid data]
|
1 (0.2%)
|
6 (0.7%)
|
0.195
|
The peak body temperature [median (25th-75th interquartile range),°C, 1303 valid data ]
|
39.3 (39.0-39.8)
|
39.4 (39.0-39.9)
|
0.177
|
Laboratory values
|
|
|
|
PCT [median (25th-75th interquartile range), ng/ml, 903 valid data]
|
0.1 (0-0.2)
|
0.1 (0-0.2)
|
0.225
|
LDH [median (25th-75th interquartile range), U/L, 912 valid data]
|
312.0 (262.5-361.0)
|
291.0 (251.9-345.0)
|
0.002
|
WBC [median (25th-75th interquartile range), ×109/L, 1376 valid data]
|
7.2 (6.0-8.8)
|
7.9 (5.6-11.3)
|
0.000
|
L [X±SD, %, 1371 valid data]
|
32.2±11.3
|
34.9±21.1
|
0.003
|
CRP [median (25th-75th interquartile range), mg/L, 1370 valid data]
|
12.0 (5.9-21.4)
|
8.8 (2.6-23.6)
|
0.000
|
N [X±SD, %, 1376 valid data]
|
57.4±13.5
|
55.0±18.7
|
0.006
|
3.3 Comparison of RMPP and GMPP patients
In the 534 M. pneumoniae -DNA positive patients, 446 cases were MPP. In MPP patients, 55 cases were RMPP (12.3%), others were GMPP patients (n=391, 87.7%).
The proportion of boys in RMPP and GMPP were 50.9% (28/55) and 57.0% (223/391), the gender ratio had no significant statistical difference between RMPP and GMPP (χ2=0.735, p=0.391). The median age of RMPP and GMPP were 5.0 and 5.2 years, respectively, with no significant statistical difference (p=0.890).
Fever duration, cough duration, and the proportion of other symptoms, including wheezing, tachypnea, pharyngalgia, chest pain, headache, hoarseness, convulsion, abdominal pain and rash had no significant differences between RMPP and GMPP (all p >0.05) (Table 3). The peak body temperature before the first visit in RMPP patients were higher than that in GMPP [39.6 (39.1-40.0) °C vs. 39.2 (38.9-39.7) °C, p=0.003].
In laboratory tests, LDH were higher in RMPP patients than in GMPP ones [332.5 (278.8-392.1) U/L vs. 310.5 (259.0-358.8) U/L, p=0.024]. PCT, CRP, WBC, neutrophil percentage, lymphocyte percentage had no significant differences between RMPP and GMPP (all p >0.05) (Table 3).
In radiological features, the proportions of thickening of lung marking bronchopneumonia, consolidation, atelectasis, plural effusion, emphysema and thickening of hilar shadow had no significant differences between RMPP and GMPP (all p >0.05) (Table 3).
In past history and family history, we investigated exposure to other fever patients within one week, patients’, parents’ and grandparents’ food and medicine allergy, patients’, parents’ and grandparents’ asthma, eczema, hay fever history, number of people living together expect the patient, sibling numbers, gravidity and parity number, preterm born, maternal breast feeding time, multiple birth. All of them had no significant differences between RMPP and GMPP (all p >0.05) (Table 3).
In treatment before the first visit, macrolides were applied to 27 (49.1%) and 163 (41.7%) patients in RMPP and GMPP, with no significant differences between them (χ2=1.081, p=0.299).
Table 3 Characteristics of RMPP and GMPP patients
|
RMPP (n=55)
|
GMPP (n=391)
|
p
|
Gender (boy/girl, n)
|
28/27
|
223/168
|
0.391
|
Age [median (25th-75th interquartile range), years old, 446 valid data]
|
5.0 (3.0-8.0)
|
5.2 (3.3-6.8)
|
0.890
|
Macrolides-resistant mutation [n (%), 446 valid data]
|
42 (76.4%)
|
368 (94.1%)
|
0.939
|
Symptoms
|
|
|
|
Fever [median (25th-75th interquartile range), day, 446 valid data]
|
4 (3-5)
|
4 (3-4)
|
0.517
|
Cough [median (25th-75th interquartile range), day, 446 valid data]
|
3 (2-5)
|
4 (2-5)
|
0.397
|
Wheeze [median (25th-75th interquartile range), day, 446 valid data]
|
0 (0-0)
|
0 (0-0)
|
0.231
|
Tachypnea [n (%), 446 valid data]
|
0 (0%)
|
2 (0.5%)
|
1.000
|
Pharyngalgia [n (%), 446 valid data]
|
0 (0%)
|
0 (0%)
|
/
|
Chest pain [n (%), 446 valid data]
|
0 (0%)
|
0 (0%)
|
/
|
Headache [n (%), 446 valid data]
|
0 (0%)
|
0 (0%)
|
/
|
Hoarseness [n (%), 446 valid data]
|
0 (0%)
|
1 (0.3%)
|
1.000
|
Convulsion [n (%)], 446 valid data
|
0 (0%)
|
0 (0%)
|
/
|
Abdominal pain [n (%), 446 valid data]
|
0 (0%)
|
0 (0%)
|
/
|
Rash [n (%), 446 valid data]
|
1 (1.8%)
|
0 (0%)
|
0.123
|
The peak body temperature [median (25th-75th interquartile range),°C , 380 valid data]
|
39.6 (39.1-40.0)
|
39.2 (38.9-39.7)
|
0.003
|
Laboratory values
|
|
|
|
PCT [median (25th-75th interquartile range), ng/ml, 342 valid data]
|
0.11 (0.05-0.24)
|
0.08 (0.04-0.14)
|
0.148
|
LDH [median (25th-75th interquartile range), U/L, 348 valid data]
|
332.5 (278.8-392.1)
|
310.5 (259.0-358.8)
|
0.024
|
WBC [median (25th-75th interquartile range), ×109/L, 439 valid data]
|
7.0 (5.9-8.4)
|
7.2 (5.9-8.8)
|
0.823
|
L [X±SD, %, 439 valid data]
|
30.8±11.7
|
33.0±11.5
|
0.181
|
CRP [median (25th-75th interquartile range), mg/L, 438 valid data]
|
15.3 (6.8-29.0)
|
11.5 (5.7-19.8)
|
0.062
|
N [X±SD, %, 439 valid data]
|
59.3±12.3
|
56.8±13.2
|
0.195
|
Radiological features [n (%)]
|
|
|
|
Thickening of lung marking (393 valid data)
|
2 (4.3%)
|
19 (5.5%)
|
1.000
|
Bronchopneumonia (446 valid data)
|
22 (40.0%)
|
152 (38.9%)
|
0.759
|
Consolidation (446 valid data)
|
28 (50.9%)
|
169 (43.2%)
|
0.436
|
Atelectasis (446 valid data)
|
1 (1.8%)
|
4 (1.0%)
|
0.709
|
Plural effusion (446 valid data)
|
3 (5.5%)
|
6 (1.5%)
|
0.177
|
Emphysema (446 valid data)
|
0 (0%)
|
1 (0.3%)
|
0.746
|
Thickening of hilar shadow (446 valid data)
|
0 (0%)
|
3 (0.8%)
|
0.681
|
Personal and family history
|
|
|
|
Exposure to other fever patients within one week [n (%), 446 valid data]
|
3 (6.1%)
|
37 (12.5%)
|
0.237
|
Food and medicine allergy [n (%), 446 valid data]
|
2 (3.9%)
|
23 (6.4%)
|
0.755
|
Asthma, eczema, hay fever history [n (%), 408 valid data]
|
3 (5.9%)
|
36 (10.1%)
|
0.450
|
Parents’ and grandparents’ food and medicine allergy [n (%), 409 valid data]
|
0 (0%)
|
1 (0.3%)
|
1.000
|
Parents’ and grandparents’ asthma, eczema, hay fever history [n (%), 409 valid data]
|
1 (2.0%)
|
7 (2.0%)
|
1.000
|
Number of people living together expect the patient [median (25th-75th interquartile range), n, 409 valid data]
|
3 (2-3)
|
3 (2-3)
|
0.572
|
Sibling numbers [median (25th-75th interquartile range), n, 357 valid data]
|
1 (0-1)
|
0 (0-1)
|
0.254
|
Gravidity order [median (25th-75th interquartile range), n, 406 valid data]
|
1 (1-2)
|
1 (1-2)
|
0.017
|
Birth order [median (25th-75th interquartile range), n, 406 valid data]
|
1 (1-2)
|
1 (1-2)
|
0.342
|
Preterm born [n (%), 394 valid data]
|
0 (0%)
|
6 (1.7%)
|
1.000
|
Maternal breast feeding [median (25th-75th interquartile range), month, 400 valid data]
|
7 (6-12)
|
9 (6-12)
|
0.924
|
Multiple birth [n (%), 408 valid data]
|
1 (2.0%)
|
5 (1.4%)
|
0.538
|
Logistic regression results was showed in Table 4. Only the peak body temperature and LDH were included. The prediction probability π= exp [-29.7+0.667×Peak body temperature (°C) + 0.004×LDH (U/L)]/{1+exp [-29.7+0.667×Peak body temperature (°C) + 0.004×LDH (U/L)]} (Fig 3). The forecast consensus percentage was 88.8%. The area under ROC curve (Fig 4) of the prediction probability π of RMPP was 0.682 (95% CI, 0.593-0.771), P<0.01. The cut-off value was 0.12. Sensitivity and specificity of the prediction probability π in cut-off value was 0.64 and 0.70, respectively.
Table 4. Logistic regression analysis for related factors predicting the RMPP
Variable
|
B
|
S.E.
|
Wald
|
P value
|
Exp (B)
|
OR
|
95%CI
|
Lower
|
Upper
|
Peak body temperature (°C)
|
.667
|
.284
|
5.522
|
.019
|
1.949
|
1.949
|
1.117
|
3.401
|
LDH (U/L)
|
.004
|
.002
|
6.547
|
.011
|
1.004
|
1.004
|
1.001
|
1.007
|
Constant
|
-29.700
|
11.178
|
7.060
|
.008
|
.000
|
|
|
|
3.4 Clinical course of RMPP
Despite 42 (76.4%) RMPP patients were found macrolides-resistant mutation positive, macrolide was applied to all of them. Doxycycline was used in 2 (3.6%) patients. Systemic corticosteroid was used in 52 (94.5%) RMPP patients. The duration of systemic corticosteroid was 5 (3-6) days. Intravenous immunoglobin was used in 2 (3.6%) patients. One patient underwent bronchoscopy because of persistent atelectasis. The total fever duration was 8 (7-9) days.