title: Hospital Clostridium difficile infection (CDI) incidence as a risk factor for hospital-associated CDI.
abstract: Environmental risk factors for Clostridium difficile infections (CDIs) have been described at the room or unit level but not the hospital level. To understand the environmental risk factors for CDI, we investigated the association between institutional- and individual-level CDI.
  
  
  
  We performed a retrospective cohort study using the Healthcare Cost and Utilization Project state inpatient databases for California (2005-2011). For each patient's hospital stay, we calculated the hospital CDI incidence rate corresponding to the patient's quarter of discharge, while excluding each patient's own CDI status. Adjusting for patient and hospital characteristics, we ran a pooled logistic regression to determine individual CDI risk attributable to the hospital's CDI rate.
  
  
  
  There were 10,329,988 patients (26,086 cases and 10,303,902 noncases) who were analyzed. We found that a percentage point increase in the CDI incidence rate a patient encountered increased the odds of CDI by a factor of 1.182.
  
  
  
  As a point of comparison, a 1-percentage point increase in the CDI incidence rate that the patient encountered had roughly the same impact on their odds of acquiring CDI as a 55.8-day increase in their length of stay or a 60-year increase in age. Patients treated in hospitals with a higher CDI rate are more likely to acquire CDI.
authors.affiliation: Department of Economics and Business, Cornell College, Mount Vernon, IA.
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Miller
authors.affiliation: Department of Pharmacy Practice and Science, University of Iowa, Iowa City, IA.
authors.forename: Linnea A
authors.initials: LA
authors.lastname: Polgreen
authors.affiliation: Department of Biostatistics, University of Iowa, Iowa City, IA.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Cavanaugh
authors.affiliation: Departments of Internal Medicine and Epidemiology, University of Iowa, Iowa City, IA. Electronic address: Philip-polgreen@uiowa.edu.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Polgreen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002140:California / Q000453:epidemiology; D016360:Clostridioides difficile / Q000302:isolation & purification*; D003015:Clostridium Infections / Q000453:epidemiology* / Q000382:microbiology*; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D006761:Hospitals; D006801:Humans; D015994:Incidence; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: Clostridium difficile infection; environment; health care–associated infection; risk