ObjectiveMycoplasma pneumoniae pneumonia (MPP) is an important disease in children. Studies have demonstrated that the levels of D-dimer are elevated in some children with MPP, especially those with thrombotic complications. However, the potential association between MPP and D-dimer remains unclear. In our study, we sought to explore the relationship between the levels of plasma D-dimer and clinical characteristics of MPP patients.MethodsRetrospective analysis was conducted on 356 patients who were hospitalized in our hospital for MPP between January 1, 2017, and December 31, 2019. According to the peak value of D-dimer, patients were divided into three groups: the normal group (D-dimer<0.55 mg/L), the mild-moderately elevated group (D-dimer 0.55–5.5 mg/L) and the severely elevated group (D-dimer >5.5 mg/L). The demographic and clinical information, radiological findings, laboratory data, and treatments of patients were compared among different groups.Results106 patients were in the normal group, 204 patients were in the mild-moderately elevated group, and 46 patients were in the severely elevated group. More severe clinical and radiographic manifestations, longer length of fever, hospital stay and antibiotic therapy duration, higher incidences of extra-pulmonary complications, refractory MPP (RMPP), severe MPP (SMPP) were found in the elevated group, when compared with the normal group (P<0.01). Meanwhile, we found that the percentage of neutrophil (N%) and CD8+ lymphocyte (CD8+%), C-reactive protein (CRP), lactate dehydrogenase (LDH), interleukin (IL)-6, IL-10, and interferon-gamma (IFN-γ) trended higher with increasing D-dimer, whereas the percentage of lymphocyte (L%) and prealbumin (PAB) trended lower (P<0.01). In addition, the proportions of patients requiring oxygen therapy, glucocorticoid, bronchoscopy, immunoglobulin use, thoracentesis, or ICU admission were significantly higher in the severely elevated group than those in the other two groups (P<0.01). Correlation analysis showed that N%, L%, CRP, LDH, IL-10, length of fever, length of stay, and length of antibiotic therapy had strong correlations with the level of D-dimer.ConclusionsMPP patients with higher levels of D-dimer had more severe clinical manifestations and needed longer duration of treatment, which might be closely related to the severity of lung inflammation after MP infection.

No abstract

Objective: To explore potential predictors of RMPP in early stage.Study design: The prospective study, multicenter study was conducted in Zhejiang, China from May 1st, 2019 to January 31st, 2020. Children aged 29 days to 14 years old, with fever time during 48 to 120 hours were included. A total of 1428 children completed the study. A questionnaire was designed to collect patients’ information. Pharyngeal swab samples were collected. M. pneumoniae DNA in pharyngeal swab specimens were detected. Whether the patients develop to RMPP were assessed. Logistic regression analyses were used to examine associations between clinical data and RMPP.Results: The ages of the patients ranged from 34 days to 13.9 years with a median 4.3 years. The positive rate of M. pneumoniae -DNA was 37.4% (534/1428), and 446 cases were Mycoplasma pneumoniae pneumonia (MPP). In MPP patients, 55 cases were RMPP (12.3%), others were general MPP (GMPP) patients (n=391, 87.7%). Only the peak body temperature before the first visit and LDH level 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, and 332.5 (278.8-392.1) U/L vs. 310.5 (259.0-358.8) U/L, p=0.024]. Logistic regression also only included the above two parameters in the prediction probability. The area under ROC curve 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.Conclusions: AND RELEVANCE A prediction probability, calculating from the peak body temperature before the first visit and LDH level for early identifying RMPP from other MPP within 2-5 days of fever duration, with a cut-off value of 0.12 may be helpful in clinical practice.