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Validation of the 3-day rule for stool bacterial tests in Japan
Masanori Kobayashi1, Akahito Sako, Toshiko Ogami
1Department of Gastroenterology, Kohnodai Hospital, National Center for Global Health and Medicine, Japan.
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.
Patients:
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.
Conclusion:
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.
Insights
The 3-day rule for diagnosing Clostridium difficile (CD) infections is effective in Japan. This guideline helps optimize testing for nosocomial diarrhea, proving useful and cost-effective.
Area of Science:
- Medical Microbiology
- Hospital Epidemiology
- Health Economics
Background:
- Stool cultures for enteric pathogens have a low positive rate in nosocomial diarrhea.
- The "3-day rule" guides Clostridium difficile (CD) toxin testing for inpatients with diarrhea after 3 days of admission.
- Previous studies on the 3-day rule have primarily focused on Western healthcare settings.
Purpose of the Study:
- To validate the utility and cost-effectiveness of the 3-day rule in a Japanese acute care hospital.
- To compare the diagnostic yield and costs of stool cultures versus CD toxin tests across different patient groups.
Main Methods:
- Retrospective analysis of stool bacterial and CD toxin test results from adult patients in 2008.
- Exclusion of specimens collected after an initial positive test.
- Categorization of patients into three groups: outpatients, inpatients hospitalized for ≤3 days, and inpatients hospitalized for ≥4 days.
Main Results:
- The positive rate for CD toxin tests was 1.9% in outpatients, 7.1% in inpatients (≤3 days), and 8.5% in inpatients (≥4 days).
- The cost per positive result for CD toxin tests was significantly lower in the inpatient groups (11,333 JPY and 9,410 JPY) compared to outpatients (43,200 JPY).
- Stool culture positivity rates decreased with longer hospital stays (14.2% outpatients, 3.6% ≤3 days, 1.3% ≥4 days).
Conclusions:
- The 3-day rule is a validated and effective strategy for diagnosing Clostridium difficile infections in Japan.
- Implementing the 3-day rule improves cost-effectiveness in diagnosing nosocomial diarrhea.
- This study provides the first validation of the 3-day rule in a non-Western acute care setting.
