Complicated Pneumonia (CP) in Children in South-East Europe

Children aged from 1 month to 18 years of age diagnosed with complicated community acquired pneumonia (pneumonia with parapneumonic effusion, necrotizing pneumonia or lung abscess) who were admitted from January 1st 2014 to April 30th 2024 to participating centers will be considered eligible for this multi-centric retrospective study.

The medical charts of all selected patients will be reviewed by medical professionals at each center and data collected in a standardized electronic database specifically created for this study to ensure consistency. Data quality will be internally monitored by the lead investigator, with periodic data validation checks to identify and resolve inconsistencies. All patient information will be stored securely in accordance with local regulations.

For every enrolled patient the following variables will be obtained: age, gender, date of admission, onset of symptoms and antibiotic treatment prior to hospitalization, comorbidities, immunization status, vital parameters on admission (heart rate, respiratory rate and percutaneous blood oxygen saturation), laboratory tests results on admission (white blood cells count, C-reactive protein concentration, blood gases, serum albumin concentration, serum lactate dehydrogenase activity), biochemical and cytological characteristics of pleural effusion (if applicable), microbiological results (culture and polymerase chain reaction) with Streptococcus pneumoniae serotype and its antimicrobial susceptibility to antibiotics, imaging (chest X-ray, CT scan, lung ultrasound), flexible bronchoscopy findings (if applicable), treatment modalities encompassing length of antibiotic therapy, use of systemic steroids, thoracic drainage, application of intrapleural fibrinolytics and surgical treatment, respiratory support information, length of hospitalization and intensive care unit stay, complications, chest radiography at follow up (at 3, 6, 12 months after discharge is available) and information on fatal/nonfatal outcome.

Primary outcome The primary outcome of this study is to estimate incidence and provide information on clinical characteristics of complicated community acquired pneumonia, particularly necrotizing pneumonia, in children and also identify possible association between microbiological isolates, immunization status and severity of clinical course.

Secondary outcomes

* Comparison of pre- and post- pneumococcal conjugate vaccine period (in selected countries) regarding the number of cases, isolated Streptococcus pneumoniae and antimicrobial resistance * Determining if high values of inflammatory markers in serum can be predictive factors for complicated clinical course * Evaluation of the effectiveness of the early introduction of intrapleural fibrinolytic therapy to length of hospital stay and incidence of complications (including bronchopleural fistula). * Use the systemic corticosteroids for empyema and associated necrotizing pneumonia and the risk for bronchopleural fistula * Evaluation of frequent use of antibiotics and higher prevalence of multi-drug resistant Streptococcus pneumoniae. * Determination of risk factors for surgical therapy

The primary outcome, incidence of complicated community acquired pneumonia, will be compared between vaccinated and non-vaccinated groups using chi-square tests for categorical variables and t-tests for continuous variables. Secondary outcomes, such as length of hospital stay and complications, will be analyzed using ANOVA and logistic regression, adjusting for potential confounders such as age and comorbidities. Subgroup analyses will assess differences in outcomes across age groups and different vaccination periods (pre- and post- 13 valent pneumococcal conjugate vaccine). Statistical significance will be defined as p\<0.05. Statistical analyses will be performed using SPSS, version 26.

• Distribution of different types of complicated community acquired pneumonia [Срок оценки: from hospital admission to discharge, lasting on average from one to three weeks.]
• Number of participants vaccinated against Streptococcus pneumoniae with pneumococcal conjugate vaccine and distribution of vaccines covering for different number of serotypes [Срок оценки: from hospital admission to discharge, lasting on average from one to three weeks.]
• Distribution of different Streptococcus pneumoniae vaccines covering for different number of serotypes [Срок оценки: from hospital admission to discharge, lasting on average from one to three weeks.]
• Duration of symptoms before hospitalization [Срок оценки: recorded at the time of hospital admission.]
• Percutaneous oxygen saturation (SpO2) [Срок оценки: recorded at the time of hospital admission.]
• Heart rate [Срок оценки: recorded at the time of hospital admission.]
• Respiratory rate [Срок оценки: recorded at the time of hospital admission.]
• White blood cells count [Срок оценки: recorded at the time of hospital admission.]
• C-reactive protein concentration [Срок оценки: recorded at the time of hospital admission.]
• Blood serum albumin concentration [Срок оценки: recorded at the time of hospital admission.]
• Serum lactate dehydrogenase activity [Срок оценки: recorded at the time of hospital admission.]
• Positivity of pleural fluid bacteriological culture and PCR (polymerase chain reaction) to bacteria (if done) [Срок оценки: from hospital admission to discharge, lasting on average from one to three weeks.]