title: Investigation to identify a resource-efficient case-control methodology for determining antibiotics associated with Clostridium difficile infection.
abstract: BACKGROUND
  Antimicrobial exposure remains an important risk factor for developing Clostridium difficile infection (CDI). Efficient method to identify antibiotics associated with CDI is important for formulating strategies to curtail their use. As a prelude to a more extensive Agency for Healthcare Research and Quality-funded project (Evaluation & Research on Antimicrobial Stewardship's Effect on Clostridium difficile), we undertook an exploratory evaluation to determine a resource-efficient method for identifying antibiotic targets for antimicrobial stewardship interventions.
  
  
  METHODS
  The study compared a series of 6 focused case-control studies. Cases consisted of patients with laboratory-confirmed CDI admitted from July-October 2009. Controls were selected from patients without CDI hospitalized during the same period. Five groups of controls were matched to cases (2:1 ratio) using group-specific matching criteria, including admission date, age, type of admission, length of stay (LOS) to discharge, and/or LOS to CDI diagnosis. The final control group was selected from patients who received antibiotics during hospitalization. Data, including demographics and antibiotic usage, were compared between case and control groups.
  
  
  RESULTS
  A total of 126 cases were matched to 6 groups of 252 controls. For control groups 1-5, the use of piperacillin and tazobactam, ceftriaxone or cefepime, ciprofloxacin or moxifloxacin, intravenous vancomycin, azithromycin, and antibiotics of last resort were significantly more frequent in case than control patients. For the final control group, the associations between ceftriaxone or cefepime, and ciprofloxacin or moxifloxacin use and CDI no longer persisted. This could in part be explained by differences in comorbidities between case and control patients even with stringent matching criteria.
  
  
  CONCLUSIONS
  Use of a simple matching strategy to conduct case-control studies is an efficient and feasible compromise strategy, especially in resource-limited settings, to identify high-risk antibiotics associated with CDI.
authors.affiliation: Montefiore Medical Center, Bronx, NY; Albert Einstein College of Medicine, Bronx, NY. Electronic address: pchung@montefiore.org.
authors.forename: Philip
authors.initials: P
authors.lastname: Chung
authors.affiliation: Montefiore Medical Center, Bronx, NY; Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Brian
authors.initials: B
authors.lastname: Currie
authors.affiliation: Montefiore Medical Center, Bronx, NY; Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Yi
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Montefiore Medical Center, Bronx, NY.
authors.forename: Moshe
authors.initials: M
authors.lastname: Talansky
authors.affiliation: Montefiore Medical Center, Bronx, NY.
authors.forename: Shakara
authors.initials: S
authors.lastname: Brown
authors.affiliation: Montefiore Medical Center, Bronx, NY; Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Belinda
authors.initials: B
authors.lastname: Ostrowsky
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D016022:Case-Control Studies; D016360:Clostridioides difficile / Q000472:pathogenicity*; D003428:Cross Infection / Q000453:epidemiology*; D004761:Enterocolitis, Pseudomembranous / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012306:Risk; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotic targets; Antimicrobial stewardship; Case control; Clostridium difficile