A Lung Ultrasound-Based Nomogram for the Prediction of Refractory Mycoplasma pneumoniae Pneumonia in Hospitalized Children

Figures & data

Figure 1 Lung ultrasound imaging. (A) The longitudinal axis dimension of lung consolidation (line a); (B) The transverse axis and sagittal axis dimensions of lung consolidation (lines b and c, respectively).

Figure 2 Study flow chart. (A) Training cohort; (B) Validation cohort.

Abbreviations: CMPP, common M. pneumoniae pneumonia; RMPP, Refractory M. pneumoniae pneumonia.

Table 1 Baseline Characteristics of All Patients in the Training and Validation Cohorts

Characters	Training Cohort (n=225)	Validation Cohort (n=90)	P value
Female, n (%)	99 (44)	50 (55.6)	0.063
Age, median (IQR), years	5.0 (3.4–6.8)	5.3 (3.5–6.6)	0.879
Weight, median (IQR), kg	19 (16–24)	21 (16–27)	0.097
Duration of fever before admission median (IQR), days	6 (4–7)	5 (4–7)	0.044
Fever duration median (IQR), days	7 (5–9)	7 (5–9)	0.981
Hyperpyrexia (%)	167 (74.2)	70 (77.8)	0.509
Chest/abdomen Pain, n (%)	33 (14.7)	8 (8.9)	0.169
Wheezing, n (%)	22 (9.8)	10 (11.1)	0.723
Rales, n (%)	121 (53.8)	51 (56.7)	0.642
WBC, median (IQR), 10^9/L	8.08 (6.21–9.89)	7.50 (6.35–9.61)	0.440
NR, n (%)	56.30 (47.50–64.50)	57.45 (50.50–62.20)	0.265
CRP, median (IQR), mg/L	13 (7–27)	17 (9–30)	0.210
ALT, median (IQR), U/L	15 (12–21)	15 (13–25)	0.385
Prealbumin, median (IQR), mg/L	111 (94–136)	114 (95–132)	0.865
LDH, median (IQR), U/L	306 (263–337)	309 (272–395)	0.08
B lines
Scattered B-lines, n (%)	3 (1.3)	1 (1.1)
Dense B-lines, n (%)	218 (96.9)	88 (97.8)
Fused B-lines, n (%)	4 (1.8)	1 (1.1)	0.09
Consolidation
Size, median (IQR), cm	4.0 (2.3–5.6)	4.4 (3.3–5.3)	0.176
Consolidation size /BSA median (IQR)	5.1 (3.2–6.9)	5.3 (3.7–6.7)	0.572
Unilateral, n (%)	195 (86.7)	80 (88.9)	0.593
Bronchogram
Air, n (%)	201 (89.3)	84 (93.3)	0.275
Liquid, n (%)	13 (5.8)	4 (4.4)	0.786
CDFI, n (%)	219 (97.3)	88 (97.8)	1.00
Pleural Effusion, n (%)	89 (39.6)	24 (26.7)	0.031

Notes: Variables are expressed as percentages or medians.

Abbreviations: CMPP, Common M. pneumoniae pneumonia; RMPP, Refractory M. pneumoniae pneumonia; IQR, Interquartile Range; WBC, White Blood Cell Count; NR, Neutrophil Ratio; CRP, C-Reactive Protein; ALT, Alanine Aminotransferase; LDH, Lactate-Dehydrogenase; Hyperpyrexia, Maximum body temperature≥39°C. Scattered B lines, the number of B lines in one rib gap≤3; Dense B-lines, The B-lines fuse with each other throughout the rib space and are difficult to distinguish and count, while the acoustic rib shadow remains visible; Fused B-lines, the entire intercostal space shows too dense B-lines, failing to deliver the acoustic rib shadow; Size of consolidation, the maximum diameter of lung consolidation; BSA, Body surface area; Consolidation size /BSA, Size of consolidation corrected by BSA; Air, the presence of bronchograms of air; Liquid, the presence of bronchograms of fluid; CDFI, Color Doppler Blood Flow Image.

Table 2 Baseline Information of the CMPP and RMPP Patients

Characters	CMPP Group (n=161)	RMPP Group (n=64)	Z	P value
Female, n (%)	74 (46.0)	25 (39.1)	0.885	0.347
Age, median (IQR), years	4.8 (3.4–6.6)	6 (3.5–7.0)	−1.466	0.143
Weight, median (IQR), kg	18 (16–25)	20 (16–24)	−0.663	0.507
Duration of fever before admission median (IQR), days	5 (4–7)	6 (5–7)	−1.772	0.076
Fever duration median (IQR), days	6 (5–7)	10 (9–13)	−9.603	<0.001
Hyperpyrexia (%)	107 (66.5)	60 (93.8)	17.826	<0.001
Chest/abdomen Pain, n (%)	19 (11.8)	14 (21.9)	3.713	0.054
Wheezing, n (%)	16 (9.9)	6 (9.4)	0.016	0.898
Rales, n (%)	89 (55.3)	32 (50.0)	0.514	0.474
WBC, median (IQR), 10^9/L	7.44 (6.09–9.14)	9.13 (7.01–11.7)	−3.406	0.001
NR, n (%)	53.70 (42.85–61.35)	62.45 (54.33–70.78)	−5.212	<0.001
CRP, median (IQR), mg/L	10 (6–19)	27 (13–47)	−6.141	<0.001
ALT, median (IQR), U/L	15 (12–19)	19 (15–30)	−3.789	<0.001
Prealbumin, median (IQR), mg/L	114 (98–142)	109 (75–120)	−2.371	0.018
LDH, median (IQR), U/L	289 (254–322)	356 (313–463)	−7.211	<0.001

Notes: Variables are expressed as percentages or medians.

Abbreviations: CMPP, Common M. pneumoniae pneumonia; RMPP, Refractory M. pneumoniae pneumonia; IQR, Interquartile Range; WBC, White Blood Cell Count; NR, Neutrophil Ratio; CRP, C-Reactive Protein; ALT, Alanine Aminotransferase; LDH, Lactate-Dehydrogenase; Hyperpyrexia, Maximum body temperature≥39°C.

Table 3 LUS Findings of the CMPP and RMPP Patients

Characters	CMPP Group (n=161)	RMPP Group (n=64)	χ^2/Z	P value
B lines
Scattered B-lines, n (%)	3 (1.9)	0 (0.0)
Dense B-lines, n (%)	154 (95.7)	64 (100)
Fused B-lines, n (%)	4 (2.5)	0 (0.0)	1.816	0.346
Consolidation
Size, median (IQR), cm	3.2 (1.7–4.6)	6.3 (5.5–8.2)	−9.868	<0.001
Consolidation Size /BSA median (IQR)	4.0 (2.0–5.8)	8.3 (6.4–10.6)	−9.277	<0.001
Unilateral, n (%)	136 (84.5)	59 (92.2)	2.359	0.125
Bronchogram
Air, n (%)	154 (95.7)	47 (73.4)	23.717	<0.001
Liquid, n (%)	3 (1.9)	10 (15.6)		<0.001
CDFI, n (%)	157 (97.5)	62 (96.9)		1.000
Pleural Effusion, n (%)	48 (29.8)	41 (64.1)	22.467	<0.001

Notes: Variables are expressed as percentages or medians.

Abbreviations: CMPP, Common M. pneumoniae pneumonia; RMPP, Refractory M. pneumoniae pneumonia; IQR, Interquartile Range; Scattered B lines, the number of B lines in one rib gap≤3; Dense B-lines, The B-lines fuse with each other throughout the rib space and are difficult to distinguish and count, while the acoustic rib shadow remains visible; Fused B-lines, the entire intercostal space shows too dense B-lines, failing to deliver the acoustic rib shadow; Size of consolidation, the maximum diameter of lung consolidation; BSA, Body surface area; Consolidation size /BSA, Size of consolidation corrected by the BSA; Air, the presence of bronchograms of air; Liquid, the presence of bronchograms of fluid; CDFI, Color Doppler Blood Flow Image.

Table 4 Stepwise Logistic Regression Analysis for the Independent Variable Predicting the RMPP

Variables	β	S.E	Wals	df	P	Odds Ratio	95% CI for OR
							Lower	Upper
Pleural Effusion	1.700	0.534	10.125	1	0.001	3.551	1.921	15.600
CRP	0.056	0.019	8.617	1	0.003	3.293	1.019	1.098
LDH	0.013	0.004	13.904	1	0.000	1.044	1.006	1.021
Consolidation size/BSA	0.662	0.119	31.101	1	0.000	1.015	1.536	2.446
Constant	−11.359	1.747	42.261	1	0.000	0.000

Abbreviations: RMPP, Refractory M. pneumoniae pneumonia; CRP, C-Reactive Protein; LDH, Lactate-Dehydrogenase; Consolidation size/BSA, Size of consolidation corrected by the BSA; BSA, Body surface area.

Figure 3 Nomogram for predicting RMPP.

Abbreviations: RMPP, Refractory M. pneumoniae pneumonia; Consolidation Size/BSA, Size of Consolidation corrected by BSA; BSA, Body surface area.

Figure 4 ROC curves. (A) Training cohort; (B) Validation cohort.

Abbreviation: AUC, the area under the ROC curves.

Figure 5 Calibration curve for predictive models. (A) Training cohort; (B) Validation cohort.