Invasive Haemophilus influenzae Disease in Adults ≥65 Years, United States, 2011.
BACKGROUND
Since the introduction of the Haemophilus influenzae serotype b vaccine, H influenzae epidemiology has shifted. In the United States, the largest burden of disease is now in adults aged ≥65 years. However, few data exist on risk factors for disease severity and outcome in this age group.


METHODS
A retrospective case-series review of invasive H influenzae infections in patients aged ≥65 years was conducted for hospitalized cases reported to Active Bacterial Core surveillance in 2011.


RESULTS
There were 299 hospitalized cases included in the analysis. The majority of cases were caused by nontypeable H influenzae, and the overall case fatality ratio (CFR) was 19.5%. Three or more underlying conditions were present in 63% of cases; 94% of cases had at least 1. Patients with chronic heart conditions (congestive heart failure, coronary artery disease, and/or atrial fibrillation) (odds ratio [OR], 3.27; 95% confidence interval [CI], 1.65-6.46), patients from private residences (OR, 8.75; 95% CI, 2.13-35.95), and patients who were not resuscitate status (OR, 2.72; 95% CI, 1.31-5.66) were more likely to be admitted to the intensive care unit (ICU). Intensive care unit admission (OR, 3.75; 95% CI, 1.71-8.22) and do not resuscitate status (OR, 12.94; 95% CI, 4.84-34.55) were significantly associated with death.


CONCLUSIONS
Within this age group, burden of disease and CFR both increased significantly as age increased. Using ICU admission as a proxy for disease severity, our findings suggest several conditions increased risk of disease severity and patients with severe disease were more likely to die. Further research is needed to determine the most effective approach to prevent H influenzae disease and mortality in older adults.
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta , Georgia.
Amy
A
Blain
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta , Georgia.
Jessica
J
MacNeil
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta , Georgia.
Xin
X
Wang
New York State Department of Health, Albany.
Nancy
N
Bennett
Department of Medicine , Emory University School of Medicine and the Atlanta VA Medical Center , Atlanta , Georgia.
Monica M
MM
Farley
Department of International Health , Johns Hopkins Bloomberg School of Public Health , Baltimore, Maryland.
Lee H
LH
Harrison
Minnesota Department of Health, St. Paul.
Catherine
C
Lexau
Colorado Department of Public Health and Environment , Denver.
Lisa
L
Miller
New Mexico Department of Health , Sante Fe.
Megin
M
Nichols
Connecticut Department of Public Health , Hartford.
Susan
S
Petit
School of Public Health , University of California , Berkley.
Arthur
A
Reingold
Department of Preventive Medicine , Vanderbilt University School of Medicine , Nashville, Tennessee.
William
W
Schaffner
Oregon Department of Human Services , Portland.
Ann
A
Thomas
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta , Georgia.
Thomas
T
Clark
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta , Georgia.
Amanda
A
Cohn
Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta , Georgia.
Elizabeth
E
Briere
Haemophilus influenzae; older adults