title: Validation of the 3-day rule for stool bacterial tests in Japan.
abstract: OBJECTIVE
  Stool cultures are expensive and time consuming, and the positive rate of enteric pathogens in cases of nosocomial diarrhea is low. The 3-day rule, whereby clinicians order a Clostridium difficile (CD) toxin test rather than a stool culture for inpatients developing diarrhea >3 days after admission, has been well studied in Western countries. The present study sought to validate the 3-day rule in an acute care hospital setting in Japan.
  
  
  METHODS
  Stool bacterial and CD toxin test results for adult patients hospitalized in an acute care hospital in 2008 were retrospectively analyzed. Specimens collected after an initial positive test were excluded. The positive rate and cost-effectiveness of the tests were compared among three patient groups.
  
  
  METHODS
  The adult patients were divided into three groups for comparison: outpatients, patients hospitalized for ≤3 days and patients hospitalized for ≥4 days.
  
  
  RESULTS
  Over the 12-month period, 1,597 stool cultures were obtained from 992 patients, and 880 CD toxin tests were performed in 529 patients. In the outpatient, inpatient ≤3 days and inpatient ≥4 days groups, the rate of positive stool cultures was 14.2%, 3.6% and 1.3% and that of positive CD toxin tests was 1.9%, 7.1% and 8.5%, respectively. The medical costs required to obtain one positive result were 9,181, 36,075 and 103,600 JPY and 43,200, 11,333 and 9,410 JPY, respectively.
  
  
  CONCLUSIONS
  The 3-day rule was validated for the first time in a setting other than a Western country. Our results revealed that the "3-day rule" is also useful and cost-effective in Japan.
authors.affiliation: Department of Gastroenterology, Kohnodai Hospital, National Center for Global Health and Medicine, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Akahito
authors.initials: A
authors.lastname: Sako
authors.forename: Toshiko
authors.initials: T
authors.lastname: Ogami
authors.forename: So
authors.initials: S
authors.lastname: Nishimura
authors.forename: Naoki
authors.initials: N
authors.lastname: Asayama
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yada
authors.forename: Naoyoshi
authors.initials: N
authors.lastname: Nagata
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakurai
authors.forename: Chizu
authors.initials: C
authors.lastname: Yokoi
authors.forename: Masao
authors.initials: M
authors.lastname: Kobayakawa
authors.forename: Mikio
authors.initials: M
authors.lastname: Yanase
authors.forename: Naohiko
authors.initials: N
authors.lastname: Masaki
authors.forename: Nozomi
authors.initials: N
authors.lastname: Takeshita
authors.forename: Naomi
authors.initials: N
authors.lastname: Uemura
mesh_terms: D000328:Adult; D000368:Aged; D016360:Clostridioides difficile / Q000302:isolation & purification*; D003362:Cost-Benefit Analysis; D003428:Cross Infection / Q000191:economics / Q000382:microbiology / Q000517:prevention & control*; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology*; D004761:Enterocolitis, Pseudomembranous / Q000175:diagnosis* / Q000191:economics / Q000382:microbiology; D005243:Feces / Q000382:microbiology*; D005260:Female; D006760:Hospitalization / Q000191:economics / Q000706:statistics & numerical data; D006801:Humans; D007297:Inpatients; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D012189:Retrospective Studies; D013997:Time Factors