Researchers developed an algorithm aimed at controlling overdiagnosis of Clostridioides difficile infections (CDIs) in patients who have received hematopoietic stem cell transplantation (HSCT). They performed a study on the use of this algorithm and reported their findings in the journal Transplantation and Cellular Therapy.

Because there are many reasons patients who have undergone HSCT may experience diarrhea and it can be difficult to distinguish the cause, the researchers had a goal of developing a tool for identifying CDI in these patients. Specifically, they aimed to reduce the use of stool submission for CDI testing and diagnosis while not negatively impacting patient outcomes.

Patients in this study were HSCT recipients who underwent precautions while hospitalized regarding air filtration, antibacterial prophylaxis, and other approaches. Testing of stool specimens for C. difficile or CDI was determined by the algorithm, which used a risk categorization approach based on subjective and objective criteria involving the patient’s clinical status and the severity of diarrhea.

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Patients with diarrhea who were considered to be of low risk were not subjected to testing but primarily received supportive care with fluids. Patients underwent testing and were not to receive loperamide if they were of moderate or high risk, or low risk with worsening diarrhea or no improvement within 48 hours.

Treatment of these patients was primarily based on results of stool testing. The algorithm was presented to clinical staff, and advanced practice providers provided feedback on its use and possible areas of improvement.

There were 149 patients evaluated in the study from the 2 years prior to the algorithm’s introduction, and 262 patients from within the first 3 years after the algorithm’s introduction. The incidence of stool submissions for C. difficile testing dropped from 38.0/1000 inpatient days before the algorithm’s inception to 20.6/1000 inpatient days after it (P <.001). Additionally, CDI diagnoses decreased from 5.5/1000 inpatient days to 2.4/1000 inpatient days after initiation of the algorithm (P =.007).

The researchers noted that use of this algorithm was not associated with adverse impacts on patients in terms of length of stay, overall survival, progression-free survival, acute graft vs host disease, readmissions after HSCT, or rates of recurrent CDI. Advanced practice providers also rated the algorithm as demonstrating high ease of use.

“Use of an algorithm defining criteria for C. difficile testing, diagnosis, and treatment can significantly decrease CDI diagnoses on a HSCT inpatient unit without apparent adverse effects,” the researchers concluded in their report.


Ford CD, Hoda D, Lopansri BK, Parra M, Sharma P, Asch J. An algorithm addressing the problem of overdiagnoses of Clostridioides difficile infections in hematopoietic stem-cell transplant recipients: effects on CDI rates and patient outcomes. Transplant Cell Ther. Accepted manuscript. Published online April 20, 2023. doi:10.1016/j.jtct.2023.04.010