Outcomes and Risk Factors for Influenza and Respiratory Syncytial Virus Lower Respiratory Tract Infections and Mortality in Patients With Lymphoma or Multiple Myeloma: A 7-Year Retrospective Cohort Study.

Background: Respiratory viral infection (RVI) is a significant complication in patients with hematologic malignancies. While risk factors of lower respiratory tract infections (LRIs) and mortality have been studied in allogeneic hematopoietic cell transplant recipients, data remain limited for patients with lymphoma and multiple myeloma (MM). We investigated outcomes and risk factors of LRI and mortality secondary to respiratory syncytial virus (RSV) or influenza virus (IFV) infections in these populations. Methods: We performed a retrospective study in adults with lymphoma or MM with RSV or IFV RVIs between 2016 and 2022. Primary outcomes were LRI and all-cause 30- and 90-day mortality. Results: We analyzed 440 patients with 490 consecutive viral episodes: 297 (61%) with MM and 193 (39%) with lymphoma, 258 (52%) were IFV-related, and 234 (48%) RSV-related (2 coinfections). At presentation, 62% were diagnosed with upper respiratory tract infection (URI) and 38% with LRI. During follow-up, 57% were hospitalized, 8% required intensive care unit transfer, and 20 (4%) died within 30 days. On multivariable analysis, RSV infection (vs IFV), current/former smoking, steroid exposure, lymphopenia (≤200 cells/mL), and high serum creatinine were associated with LRI. MM (vs lymphoma) diagnosis, current/former smoking, lymphopenia, and nosocomial infection were associated with 30-day mortality, whereas LRI (vs URI), current/former smoking, and lymphopenia were associated with 90-day mortality. Conclusions: We described a high burden of IFV and RSV infections in patients with lymphoma and MM and found risk factors associated with LRI and mortality. These factors could potentially identify high-risk patients, enabling better and prompt management strategies.