Age-Stratified Clinical Characteristics and Risk Factors for Lobar Pneumonia in Children with Mycoplasma pneumoniae Pneumonia postprint

Abstract: Background　Mycoplasma pneumoniae（MP） pneumonia（MPP） is community-acquired pneumonia（CAP）occurring commonly in children in our country. The clinical features and treatment outcomes of MMP are thought to be closely associated with age and radiographic progression. However，studies have investigated the age‐specific combined with radiographic features in patients with MP pneumonia are scarce. Objectives　We aimed to investigate the clinical manifestations in children with Mycoplasma pneumoniae pneumonia at different ages and to determine the risk factors for lobar pneumonia so as to provide reference for its precise treatment. Methods　This was a retrospective study. The clinical data of 895 children with MPP who were hospitalized at Hunan Provincial People's Hospital between August 2023 and April 2024 were included in the study and divided into the group with aged <5 years old and the group with aged >5 years old according to age. Different age groups were further divided into subgroups（lobar pneumonia and non-lobar pneumonia） according to the chest imaging findings. The clinical data，laboratory findings，treatments and outcomes were collected and analyzed. To use the method based on TaqMan fluorescent probe real-time PCR for detecting MP-DNA and drug resistant gene. Multivariate logistic regression models were used to identify the risk factors for lobar pneumonia. Results　Of the 895 patients with MPP we studied，418 of whom（46.7%） were male，477 of whom（53.3%） were female. The median age of the children was 7.09 years（interquartile range，5.1 to 8.9）.The clinical data of 218（24.4%）patients with MPP aged <5 years old and further divided into the study subgroup with 164（18.3%） cases （non-lobar pneumonia） and 54（6.0%） cases（lobar pneumonia）.The clinical data of 677（75.6%）patients with MPP aged ≥ 5 years old，and further divided into the study subgroup with 304（34.0%） cases（non-lobar pneumonia） and 373（41.7%） cases（lobar pneumonia）. The proportion and duration of cough, fever, rales, weakened breathing sounds, headache, dizziness, fever peak ≥ 39.0℃ , sore throat, neutrophil/lymphocyte ratio（NLR）, platelet count/lymphocyte ratio（PLR）, D-dimer level, mycoplasma（MP） resistance rate, bronchoscopy ratio, methylprednisolone treatment, and lobular pneumonia in children aged ≥ 5 years The proportion of nasal cannula oxygen inhalation was higher than that of the < 5-year-old group, while the ratios of wheezing, concave sign, lactate dehydrogenase (LDH) level, the use of gamma globulin, non-invasive mechanical ventilation (CPAP), and admission to the pediatric intensive care unit (PICU) were lower than those of the < 5-year-old group，with statistically significant differences （P<0.05）. In the <5-year-old lobar pneumonia subgroup, the proportions of allergic constitution, fever peak ≥ 39° C, wheezing, drug resistance, and oxygen therapy were lower than those in the <5-year-old non-lobar pneumonia subgroup, while the median age, proportion of decreased pulmonary breath sounds, white blood cell count（WBC） and length of hospital stay were higher than those in the <5-year-old non-lobar pneumonia subgroup, with statistically significant differences （P<0.05）. In the ≥ 5-year-old lobar pneumonia subgroup, the proportions of allergic constitution, fever peak ≥ 39 ° C, proportion of decreased breath sounds, D-dimer, drug resistance, bronchoscopy, methylprednisolone, and length of hospital stay were higher than those in the ≥ 5-year-old non-lobar pneumonia subgroup, while the proportions of wheezing, three-concave sign, and oxygen therapy were lower than those in the ≥ 5-year-old non-lobar pneumonia subgroup, with statistically significant differences（P<0.05）. Multivariate Logistic stepwise regression analysis showed that age ≥ 5 years, allergic constitution, fever peak ≥ 39.0°C, NLR, and MP drug resistance were risk factors for lobar pneumonia（P<0.05）. Conclusions　The pulmonary signs in the <5-year-old age group are more obvious, requiring more oxygen therapy and PICU support; while the extrapulmonary symptoms in the ≥ 5-year-old group are more prominent, with a longer hospital stay, prone to progression to lobar pneumonia, a high incidence of drug resistance, and more common needs for glucocorticoids and bronchoalveolar lavage （BAL） treatment. Age ≥ 5 years, allergic constitution, fever peak ≥ 39.0° C, NLR, and drug resistance are risk factors for the occurrence of lobar pneumonia.