Risk Factors and Medical Resource Utilization of Respiratory Syncytial Virus, Human Metapneumovirus and Influenza Related Hospitalizations in Adults – A Global Study During the 2017-2019 Epidemic Seasons (Hospitalized Acute Respiratory Tract Infection [HARTI] Study)

Background Respiratory syncytial virus (RSV), human metapneumovirus (hMPV) and influenza are respiratory pathogens leading to hospitalization in adults. Understanding disease burden is limited to data from single-center or one-season studies in elderly patients. The HARTI study allows comparison of risk factors for progression to severe disease and medical resources utilization (MRU) during and post-hospitalization in adults diagnosed with influenza, RSV, or hMPV. Methods This was a prospective global study in adults hospitalized with acute respiratory tract infection (40 centers, 12 countries). Participants with influenza, RSV, or hMPV were enrolled in a substudy and followed up to three months post-discharge. Results Overall, 366 influenza, 238 RSV, and 100 hMPV-infected participants enrolled in the substudy. RSV participants were older, had greater frequency of risk factors, and longer duration of symptoms prior to hospitalization than influenza participants. RSV and hMPV groups received more bronchodilators, corticosteroids, and oxygen supplementation. No significant differences in intensive care unit admissions or complications were observed. Readmission occurred in 20-33% of patients within three months post-discharge, with highest rates for RSV and hMPV. In-hospital death occurred in 2.5% RSV, 1.6% influenza, and 2% hMPV participants. In multivariate analyses, length of stay was independently associated with country, renal disease, and increased age; probability of receiving supplemental oxygen was associated with pathogen (hMPV>RSV>influenza), abnormal chest x-ray, and increased age. Conclusions Although influenza is more frequent, the HARTI study demonstrates greater frequency of underlying risk factors and MRU for RSV and hMPV versus influenza in hospitalized adults, indicating need for effective interventions.