Comparison of Hospitalized Solid Organ Transplant Recipients and Nonimmunocompromised Patients With Pandemic H1N1 Infection: A Retrospective Cohort Study

Background. Pandemic H1N1 influenza has been associated with a worldwide outbreak of febrile respiratory illness. Although impaired cell mediated immunity, such as that caused by transplant immunosuppression, has been identified as a risk factor for severe infection with this virus, the course of this infection has not been adequately characterized in solid organ transplant (SOT) recipients in comparison with nontransplanted controls. We report our experience with severe pH1N1 infection in transplant recipients and compare this group with nonimmunosuppressed patients. Methods. Data were retrospectively collected on all patients admitted to our institution with proven pH1N1 infection. Clinical characteristics, treatments, and outcomes were compared between SOT recipients and nonimmunocompromised controls. Results. Seventeen SOT recipients and 49 controls were identified. The control group had higher baseline rates of asthma (P=0.02) and smoking (P=0.05) at baseline. No difference in clinical features of H1N1 infection was detected except for a greater prevalence of wheeze in the non-SOT group (P=0.02). No statistical differences in outcomes could be detected between the groups. Several markers of severity, including use of high frequency oscillatory ventilation, extracorporeal membrane oxygenation, and death were slightly more frequent in the control group. Conclusion. SOT recipients admitted to hospital with pH1N1 infection did not have significantly more severe outcomes of their infection compared with their nonimmunocompromised counterparts, despite their immune suppressed status.