Determinants of Clostridium difficile Infection Incidence Across Diverse United States Geographic Locations.
BACKGROUND
Clostridium difficile infection (CDI) is no longer restricted to hospital settings, and population-based incidence measures are needed. Understanding the determinants of CDI incidence will allow for more meaningful comparisons of rates and accurate national estimates.


METHODS
Data from active population- and laboratory-based CDI surveillance in 7 US states were used to identify CDI cases (ie, residents with positive C difficile stool specimen without a positive test in the prior 8 weeks). Cases were classified as community-associated (CA) if stool was collected as outpatients or ≤3 days of admission and no overnight healthcare facility stay in the past 12 weeks; otherwise, cases were classified as healthcare-associated (HA). Two regression models, one for CA-CDI and another for HA-CDI, were built to evaluate predictors of high CDI incidence. Site-specific incidence was adjusted based on the regression models.


RESULTS
Of 10 062 cases identified, 32% were CA. Crude incidence varied by geographic area; CA-CDI ranged from 28.2 to 79.1/100 000 and HA-CDI ranged from 45.7 to 155.9/100 000. Independent predictors of higher CA-CDI incidence were older age, white race, female gender, and nucleic acid amplification test (NAAT) use. For HA-CDI, older age and a greater number of inpatient-days were predictors. After adjusting for relevant predictors, the range of incidence narrowed greatly; CA-CDI rates ranged from 30.7 to 41.3/100 000 and HA-CDI rates ranged from 58.5 to 94.8/100 000.


CONCLUSIONS
Differences in CDI incidence across geographic areas can be partially explained by differences in NAAT use, age, race, sex, and inpatient-days. Variation in antimicrobial use may contribute to the remaining differences in incidence.
Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
Fernanda C
FC
Lessa
Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
Yi
Y
Mu
Division of Infectious Diseases , University of California, San Francisco School of Medicine.
Lisa G
LG
Winston
Division of Infectious Diseases , University of Rochester Medical Center , New York.
Ghinwa K
GK
Dumyati
Division of Infectious Diseases , Emory University School of Medicine , Atlanta, Georgia ; Atlanta Veterans Affairs Medical Center , Georgia.
Monica M
MM
Farley
Oregon Health Authority, Public Health Division , Portland.
Zintars G
ZG
Beldavs
Colorado Department of Public Health and Environment, Denver.
Kelly
K
Kast
Centers for Disease Control and Prevention Epidemiology Field Officer Assigned to Minnesota Department of Health, St. Paul, Minnesota.
Stacy M
SM
Holzbauer
Emerging Infections Program , Yale University School of Public Health , New Haven, Connecticut.
James I
JI
Meek
Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia ; Atlanta Research and Education Foundation , Georgia.
Jessica
J
Cohen
Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
L Clifford
LC
McDonald
Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
Scott K
SK
Fridkin