Age-related heterogeneity in diagnosis-coded pediatric Mycoplasma pneumoniae-associated hospitalizations and PICU-associated care: a single-center retrospective study

Introduction Post-pandemic re-emergence of Mycoplasma pneumoniae has raised concern about pediatric hospital burden and intensive-care demand. We described temporal trends, age-stratified diagnosis-coded phenotypes, pathogen-related coded co-diagnoses, and variables associated with PICU-associated hospitalization. Methods We conducted a single-center retrospective study based on diagnosis-coded discharge records from a tertiary maternal and child health hospital in Hubei, China. Hospitalization records of children aged 29 days to <18 years with finalized diagnosis-coded M. pneumoniae -associated illness from June 2020 to March 2026 were screened; neonatal, adult, and manually verified repeated records were excluded. A stratified chart-validation subset ( n = 762) summarized microbiological evidence and selected coding-derived variables. Results The analytic dataset included 33,047 pediatric hospitalization records; 16,848 (51.0%) were male and 872 (2.6%) were PICU-associated. Monthly records peaked in November 2023 (2,282), whereas PICU-associated records and rate peaked in October 2023 (99; 4.95%). Respiratory failure/hypoxemia was recorded in 6.6% of the 1–<12 mo group versus 1.3% of the 72–<144 mo group; coded sepsis/septicemia in 11.2% versus 5.9%; and cardiac abnormality/coded myocardial involvement in 25.0% versus 15.6%. Atelectasis and consolidation peaked in the 72–<144 mo group (24.1 and 13.0%). The most common pathogen-related coded co-diagnoses were respiratory syncytial virus (2,096; 6.3%), rhinovirus (2,031; 6.1%), Haemophilus influenzae (1,351; 4.1%), adenovirus (1,348; 4.1%), and influenza virus (956; 2.9%). In the extended exploratory model, age 1–<12 mo (aOR, 2.59; 95% CI, 2.07–3.24), age 12–<36 mo (aOR, 1.70; 95% CI, 1.40–2.07), influenza virus (aOR, 2.07; 95% CI, 1.50–2.86), respiratory syncytial virus (aOR, 1.83; 95% CI, 1.43–2.35), and major chronic/congenital comorbidity (aOR, 8.07; 95% CI, 6.69–9.74) were associated with PICU-associated hospitalization. Conclusion Diagnosis-coded pediatric M. pneumoniae -associated hospitalization records increased after June 2023 and peaked in November 2023, with age-structured coded phenotype patterns and measurable PICU-associated burden. Findings represent hospital-based diagnosis-coded patterns, not laboratory-adjudicated incident infections or population incidence.