Respiratory Synctial Virus (RSV) Infection in Hematopoietic Stem Cell Transplant (HCT) Recipients: Risk Factors for Acquisition and Lower Respiratory Tract Disease, and Impact on Mortality.

RSV lower respiratory tract disease (LRTD) is a serious complication after HCT. Risk factors for virus acquisition and progression from RSV upper respiratory tract infection (URI) to RSV LRTD are poorly defined. A targeted surveillance system consisting of routine virologic evaluation for RSV (DFA, shell vial assay, culture) in HCT recipients with URI symptoms was instituted in 10/89. We retrospectively analyzed risk factors of RSV acquisition and the development of RSV-LRTD among patients with RSV-URI between 10/89 and 7/02. From 10/94 to 7/97, patients with RSV-URI received preemptive aerosolized ribavirin (2g/day) for 5–7 d; some patients received full-dose preemptive ribavirin (6g/day). All results are from multivariable models. One hundred forty-seven of 4717 (3.1%) patients were diagnosed with RSV URI and/or LRTD during the first 100 days after HCT. Risk factors for RSV acquisition included bone marrow vs. peripheral blood stem cell (PBSC) (1.7, P=0.01), winter season (P<0.0001), the years 1993 and 1997 when 2 outbreaks occurred (HR 1.7, P=0.01), male sex (HR 1.4, P=0.06). Laminar airflow rooms (HR 0.5, P=0.004) and the period after 1997 (HR 0.65, P=0.09) were protective against acquisition (after 1997, we started to restrict patient contact with staff and caretakers who had an URI with uncontrolled secretions). Risk factors for RSV-LRTD among infected patients included age > 20 year (OR 3.2, P=0.02) and lymphocytopenia < 100/mm³ (OR 4.7, P=0.0005). To assess risk factors for progression from RSV-URI to LRTD, patients who presented with RSV-URI were examined. Lymphocytopenia < 100/mm³ was the only statistically significant factor (OR 14, P<0.001) associated with progression; use of preemptive ribavirin (low- or high-dose) was not statistically significantly associated with a lower progression rate. The development of RSV LRTD as a time-dependent variable was associated with increased mortality after HCT (HR 2.2, p < 0.001), after controlling for age, underlying disease status, donor match and type, conditioning regimen, stem cell source, and CMV serostatus. Thus, RSV acquisition is less common with PBSC transplantation and in a strict isolation setting. Restricting recipients’ contact to people with uncontrolled respiratory secretions in the outpatient setting may be beneficial; further studies are needed to confirm this. Lymphocytopenia is an important risk factor for progression from URI to LRTD and RSV-LRTD is independently associated with mortality after HCT.