Clinical and laboratory examination characteristics in 93 severe MPP patients
A total of 93 patients (45 males, 48 females) fulfilled the severe MPP diagnostic criteria from January 2016 to December 2018. Descriptive statistics of study population are shown in table 1.The mean age was 6.16 ± 0.33 years, and 63 (67.7%) patients had pulmonary complication, including lobe atelectasis, medium or large pleura effusion and necrotizing pneumonia. 53(56.9%) patients had single pulmonary complication. High loading of MP in NPA was found in 73 (78.4) patients. Flexible bronchoscopy was performed in 86 (92.3%) patients. Large secretion (grade 6) was found in 27 (31.3%) patients, moderate secretion (grade 5) was found in 41 (47.7%)patients, mild secretion (grade 4) was found in 10 (11.6%) patients and minimal secretion was found in 8 (9.4%) patients. 9 (9.7%) patients received low-dose corticosteroid therapy. 63 (67.7%) patients returned for their follow-up chest radiography at least once, and complete or near complete resolution was reported in 37 (58.7%) patients.
We compared age, total fever duration and laboratory examinations in SMPP patients with and without pulmonary complications and the data are shown in table 2.SMPP patients with pulmonary complication were associated with age, total fever days, % Neutrophils in blood sample, C-reactive protein (CRP), procalcitonin(PCT),D-dimer, lactic dehydrogenase (LDH),albumin,LDH to albumin ratio (LAR) and high load of MP in BALF when compared with those of no pulmonary complications. Other variables (MP loading in NPA, airway secretion condition and White blood cell count) showed no difference. There was a tendency that patients of corticosteroid therapy were higher in pulmonary complication group (9/63 vs 0/30,P = 0.0537)
Laboratory examination characteristics and risk indicators of SMPP with different pulmonary complications
Cases of single pulmonary complication were selected, data were analyzed and presented in table 3. There were significant differences in total fever duration, CRP, D-dimer,LDH,albumin and LAR among lobe atelectasis, pleural effusion and necrotizing pneumonia group. Percentage of large and moderate airway section cases in atelectasis, pleural effusion and necrotizing pneumonia group was 68.2%(13/19), 84.6%(22/26) and87.5% (7/8) respectively. Compared with lobe atelectasis group, higher level of total fever duration, CRP, D-dimer,LDH and LAR were found in pleural effusion group with significant differences as well as those of necrotizing pneumonia group except LDH. These variants in lobe atelectasis group showed no difference with those of no pulmonary complication group except age (6.89 ± 0.51 n = 19 vs 5.07 ± 0.45 n = 30, P = 0.0129).To find some indicators to predict the risk of pleural effusion and necrotizing pneumonia in severe MPP patients, we compared the difference of various laboratory indicators between each group and no pulmonary complication group.Both D-dimer (OR = 1.314,95%CI = 1.042 to 1.658,P = 0.021) and LAR(OR:1.215,95%CI 1.054 to 1.401, P = 0.007)was significant indicator in the multivariable logistic regression model for predicting medium or large pleural effusion in SMPP patients and only D-dimer(OR = 1.468, 95%CI = 1.139 to 1.892, P = 0.003) was significant indicator for predicting necrotizing pneumonia.
Time and indicators of chest radiography resolution in SMPP patients
Table 4 presents the time of complete and near complete chest radiography resolution in severe MPP patients. Radiographic clearance in 4 weeks was shown in 86.6% (13/15) patients without pulmonary complication patients. 72.7% (16/22) patients with pulmonary complication had radiographic clearance in 12 weeks. The resolution time of pulmonary complication group was significant longer than no pulmonary complication group (1.16 ± 0.15 n = 15 vs 2.43 ± 0.44 n = 22, P = 0.0276), but there was no difference among atelectasis group (2.46 ± 0.49 months n = 15), pleural effusion group (2.38 ± 0.73 months n = 9) and necrotizing pneumonia group (3.66 ± 2.1 months n = 3) as well as single complication group compared with multiple complications group(2.25 ± 0.42 n = 18 vs 3.25 ± 1.60 n = 4, P = 0.3943).
We further analyzed the laboratory data in no complication patients without radiograhic resolution in 4 weeks. Statistic analysis showed that D-dimer (5.21 ± 2.49 n = 4 vs 1.11 ± 0.26 n = 13，t = 4,p = 0.0149), LDH (553.80 ± 37.91 n = 4 vs 347.10 ± 25.45 n = 13,P = 0.001) and LAR (15.62 ± 1.98 n = 4 vs 8.91 ± 0.74 n = 13,P = 0.0013) were significant higher in no complication patients with radiograhic resolution > 4 weeks compared with those who had radiograhic resolution ≤ 4 weeks. Percentage of large and moderate airway secretion patients by first-time FB test was not different between these two groups (4/4 vs 11/13, P = 1). LDH(OR = 1.024,95%CI = 0.999 to 1.051, P = 0.059) might be an predictor in the multivariable logistic regression for long time resolution in no complication group. We also found that there were 27.2% (6/22) pulmonary complication patients with radiographic resolution > 12 weeks, including one lobe atelectasis patient, four pleural effusion patient and one patient of pleural effusion combined with necrotizing. Fever duration (12.00 ± 0.894 n = 6 vs 8.44 ± 0.57 n = 16,P = 0.0044), D-dimer (9.92 ± 2.90 n = 6 vs 3.96 ± 0.91 n = 16,P = 0.0155) and LDH (748.70 ± 178.60 n = 6 vs 484.50 ± 45.81 n = 16,P = 0.0496) were significant different between complication groups with radiographic resolution > 12 weeks or ≤ 12 weeks. Percentage of large and moderate airway secretion by first-time FB test was higher in complication patients with ≤ 12 weeks radiographic resolution (3/6 vs 16/16, P = 0.013) compared with those of > 12 weeks radiographic clearance.D-dimer (OR = 1.241,95%CI = 1.009 to 1.527, P = 0.041) was an predictor in the multivariable logistic regression model for > 12 weeks resolution in complication group.