Retrospective Observational Multicenter Study on the Burden of Hospitalized Patients With Respiratory Tract Infection

This multicenter retrospective real-world data study will evaluate the burden of respiratory tract infection (RTI)-related hospitalizations in up to 10 Dutch hospitals between 2018 and 2026. The study aims to quantify: * Hospitalization rates * Healthcare resource utilization (LOS, ICU admissions, readmissions) * Clinical outcomes (including mortality) * Direct healthcare costs * Pathogen-specific burden (e.g., RSV, influenza, SARS-CoV-2) Using linked hospital, laboratory, and administrative data, outcomes will be analyzed by age group, comorbidities, pathogen, and respiratory season. The expected cohort size is approximately 60,000-70,000 patients. The results will provide evidence to support Dutch public health policy, including RSV immunization strategies, healthcare capacity planning, and antimicrobial stewardship.

Inclusion Criteria: * All patients with any care activity during a hospitalisation registered under any primary or secondary RTI ICD-10 code; hospital admission beginning within April 2018 - July 2026. Exclusion Criteria: * Patients who have formally objected to the use of their hospital data for scientific research.