Table 1 The demographic and clinical characteristics of all cases with M. pneumoniae pneumonia

Age (years)

7.3 (5.6, 9.1)

6.6 (4.7, 8.2)

< 0.01

Sex, male

455 (50.1%)

44 (61.1%)

0.07

Atopic conditions, n (%)

249 (27.3%)

45 (62.5%)

< 0.001

Family history of atopic disease

143 (15.7%)

14 (19.4%)

0.41

 Atopic dermatitis

137 (15.1%)

15 (20.8%)

0.19

 Allergic rhinitis

86 (9.5%)

29 (40.3%)

< 0.001

 Asthma

29 (3.2%)

9 (12.5%)

< 0.001

Acute lower pulmonary infections stage

 Symptoms

  Fever

901 (99.1%)

72 (100%)

NA

  Cough

909 (100%)

72 (100%)

NA

  Wheezing and/or dyspnea

91 (10.0%)

16 (22.2%)

0.001

Duration of fever (days)

8 (5, 10)

10 (8, 14)

< 0.001

Radiologic characteristics on CT scan, n (%)

 `Large lobar consolidation

352 (38.7%)

50 (69.4%)

< 0.001

 Diffuse bronchiolitis

74 (8.1%)

18 (25%)

< 0.001

Laboratory findings

 WBC count (1 × 10⁹/L)

7.6 (5.5, 9.7)

8.7 (6.6, 11.7)

0.03

 CRP (mg/L)

19 (11, 36)

57 (27, 94)

< 0.001

 D-dimer (ng/mL)

0.3 (0.2, 0.6)

1.0 (0.5, 3.3)

< 0.001

 ALT (IU/L)

15 (12, 23)

23 (17, 68)

< 0.001

 LDH (IU/L)

308 (268, 379)

471 (326, 809)

< 0.001

 Eosinophil count (1 × 10⁹/L)

0.04 (0.02, 0.05)

0.08 (0.04, 0.13)

0.15

 Eosinophil count > 300/µl

9 (3.0%)

4 (9.3%)

0.10

 IgE (IU/L)

40.9 (23.6, 76.1)

58.8 (30.1, 137.3)

0.09

Co-infection, n (%)

109 (11.9%)

23 (31.9%)

< 0.001

 Adenovirus

10 (1.1%)

8 (11.1%)

< 0.001

 Bacteria

79 (8.7%)

15 (20.8%)

0.001

 Other virus

42 (4.6%)

4 (5.5%)

0.72

Treatment, n (%)

 Non-invasive/ invasive ventilation

20 (2.2%)

18 (25.0%)

< 0.001

 Glucocorticoid

696 (76.6%)

70 (97.2%)

NA

 Bronchoscopy

683 (75.1%)

70 (97.2%)

NA

 Bronchial mucus plug (Bronchoscopy), n (%)

217 (23.9%)

42 (58.3%)

< 0.001