Clinical Characteristics and Outcomes of Influenza-Associated Late-Onset Severe Pneumonia After Allogeneic Hematopoietic Stem Cell Transplantation.

BACKGROUND

Late-onset severe pneumonia (LOSP) is one of the most important causes of mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The influenza virus is a frequent viral pathogen in patients receiving allo-HSCT, accounting for at least 30% of all respiratory viral infections. We aimed to identify the clinical characteristics and outcomes of influenza-associated LOSP after allo-HSCT.

METHODS

This study enrolled 23 patients who underwent allo-HSCT at the Peking University Institute of Hematology and were subsequently diagnosed with influenza-associated LOSP. Survival analysis was conducted via the Kaplan‒Meier method. Potential risk factors for survival and mortality following influenza-associated LOSP were evaluated through univariate and multivariate Cox regression analyses.

RESULTS

Among the patients, 39.1% (n = 9) died following influenza-associated LOSP. The median time from allo-HSCT to influenza infection was 269 days (range 100-3979 days), and the median time from the onset of influenza symptoms to influenza-associated LOSP was 5 days (range 0-38 days). The most common clinical manifestations were fever (95.7%), cough (56.5%), and expectoration (34.8%). After antiviral therapy, the median time for the influenza virus to turn negative was 11 days (range, 4-34 days). The 100-day cumulative incidence of influenza-associated LOSP-related mortality was 30.9% (95% CI 11.3%-50.5%). The probability of overall survival at 100 days after influenza-associated LOSP was 59.1% (95% CI 41.5%-84.0%).

CONCLUSIONS

This study presents the first comprehensive analysis of the clinical characteristics and outcomes associated with influenza-related LOSP following allo-HSCT. Additionally, our findings highlight the treatment strategies and prognostic factors associated with influenza-associated LOSP.