Invasive Haemophilus influenzae in the United States, 1999–2008: Epidemiology and outcomes

Summary Objectives Introduction of the Haemophilus influenzae type b (Hib) conjugate vaccine has resulted in a dramatic reduction of Hib disease in the U.S. and an increase in the relative importance of infections caused by nontypeable strains. The current project describes the characteristics and clinical outcomes of pediatric and adult patients with invasive H. influenzae (HI) and, through multivariable analysis, identifies risk factors for in-hospital mortality. Methods HI cases were identified during 1999–2008 through active surveillance as part of Active Bacterial Core surveillance (ABCs). Multivariable analysis was performed with logistic regression to identify factors predictive of in-hospital death. Results 4839 cases of HI were identified from 1999–2008. Children accounted for 17.1% of cases and adults 82.9%. Underlying conditions were present in 20.7% of children and 74.8% of adults. In-hospital mortality was highest in cases ≥65 years (21.9%) and