title: Prospective derivation and validation of a clinical prediction rule for recurrent Clostridium difficile infection.
abstract: OBJECTIVE
  Prevention of recurrent Clostridium difficile infection (CDI) is a substantial therapeutic challenge. A previous prospective study of 63 patients with CDI identified risk factors associated with recurrence. This study aimed to develop a prediction rule for recurrent CDI using the above derivation cohort and prospectively evaluate the performance of this rule in an independent validation cohort.
  
  
  METHODS
  The clinical prediction rule was developed by multivariate logistic regression analysis and included the following variables: age>65 years, severe or fulminant illness (by the Horn index), and additional antibiotic use after CDI therapy. A second rule combined data on serum concentrations of immunoglobulin G (IgG) against toxin A with the clinical predictors. Both rules were then evaluated prospectively in an independent cohort of 89 patients with CDI.
  
  
  RESULTS
  The clinical prediction rule discriminated between patients with and without recurrent CDI, with an area under the curve of the receiver-operating-characteristic curve of 0.83 (95% confidence interval [CI]: 0.70-0.95) in the derivation cohort and 0.80 (95% CI: 0.67-0.92) in the validation cohort. The rule correctly classified 77.3% (95% CI: 62.2%-88.5%) and 71.9% (95% CI: 59.2%-82.4%) of patients in the derivation and validation cohorts, respectively. The combined rule performed well in the derivation cohort but not in the validation cohort (area under the curve of the receiver-operating-characteristic curve, 0.89 vs 0.62; diagnostic accuracy, 93.8% vs 69.2%, respectively).
  
  
  CONCLUSIONS
  We prospectively derived and validated a clinical prediction rule for recurrent CDI that is simple, reliable, and accurate and can be used to identify high-risk patients most likely to benefit from measures to prevent recurrence.
authors.affiliation: Division of Gastroenterology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
authors.forename: Mary Y
authors.initials: MY
authors.lastname: Hu
authors.forename: Kianoosh
authors.initials: K
authors.lastname: Katchar
authors.forename: Lorraine
authors.initials: L
authors.lastname: Kyne
authors.forename: Seema
authors.initials: S
authors.lastname: Maroo
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Tummala
authors.forename: Valley
authors.initials: V
authors.lastname: Dreisbach
authors.forename: Hua
authors.initials: H
authors.lastname: Xu
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Leffler
authors.forename: Ciarán P
authors.initials: CP
authors.lastname: Kelly
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001427:Bacterial Toxins / Q000276:immunology; D016360:Clostridioides difficile / Q000472:pathogenicity*; D004761:Enterocolitis, Pseudomembranous / Q000097:blood / Q000453:epidemiology* / Q000517:prevention & control*; D004768:Enterotoxins / Q000276:immunology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012307:Risk Factors; D055502:Secondary Prevention; D012680:Sensitivity and Specificity
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004768:Enterotoxins; D007074:Immunoglobulin G; C041348:tcdA protein, Clostridium difficile