title: Impact of change to molecular testing for Clostridium difficile infection on healthcare facility-associated incidence rates.
abstract: BACKGROUND
  Change from nonmolecular to molecular testing techniques is thought to contribute to the increasing trend in incidence of Clostridium difficile infection (CDI); however the degree of effect attributed to this versus other time-related epidemiologic factors is unclear.
  
  
  METHODS
  We compared the relative change in incidence rate (IRR) of healthcare facility-associated (HCFA) CDI among hospitals in the Duke Infection Control Outreach Network before and after the date of switch from nonmolecular tests to polymerase chain reaction (PCR) using prospectively collected surveillance data from July 2009 to December 2011. Data from 10 hospitals that switched and 22 control hospitals were included. Individual hospital estimates were determined using Poisson regression. We used an interrupted time series approach to develop a Poisson mixed-effects model. Additional regression adjustments were made for clustering and proportion of intensive care unit patient-days. The variable for PCR was treated as a fixed effect; other modeled variables were random effects.
  
  
  RESULTS
  For those hospitals that switched to PCR, mean incidence rate of HCFA CDI before the switch was 6.0 CDIs per 10,000 patient-days compared with 9.6 CDIs per 10,000 patient-days after the switch. Estimates of hospital-specific IRR that compared after the switch with before the switch ranged from 0.89 (95% confidence interval [CI], 0.32-2.44) to 6.91 (95% CI, 1.12-42.54). After adjustment in the mixed-effects model, the overall IRR comparing CDI incidence after the switch to before the switch was 1.56 (95% CI, 1.28-1.90). Time-trend variables did not reach statistical significance.
  
  
  CONCLUSIONS
  Hospitals that switched from nonmolecular to molecular tests experienced an approximate 56% increase in the rate of HCFA CDI after testing change.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina.
authors.forename: Rebekah W
authors.initials: RW
authors.lastname: Moehring
authors.forename: Eric T
authors.initials: ET
authors.lastname: Lofgren
authors.forename: Deverick J
authors.initials: DJ
authors.lastname: Anderson
mesh_terms: D016360:Clostridioides difficile / Q000235:genetics / Q000302:isolation & purification*; D003428:Cross Infection / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D004269:DNA, Bacterial / Q000302:isolation & purification*; D004761:Enterocolitis, Pseudomembranous / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D016133:Polymerase Chain Reaction; D011159:Population Surveillance; D015144:Southeastern United States / Q000453:epidemiology
chemical_list: D004269:DNA, Bacterial
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