Work-up for infectious diarrhea after allogeneic hematopoietic stem cell transplantation: single specimen testing results in cost savings without compromising diagnostic yield.

BACKGROUND: Diarrhea is a common complication of allogeneic bone marrow transplantation. Microbiologic stool studies are frequently ordered to rule out infectious etiology. The utility of examining multiple stool specimens per diarrheal episode has not been examined.
METHODS: . We performed a retrospective review of 169 adult and pediatric patients who underwent hematopoietic stem cell transplantation at Memorial Sloan-Kettering Cancer Center from January 1, 2000 though December 31, 2001, who had at least 1 microbiologic stool study. We report on the incidence of enteric pathogens in our population and diagnostic yield of stool studies. A diarrheal episode was defined as a 14-day period from the date of the first stool study. Cost savings analysis was based on projected savings from implementation of proposed guidelines to the study population.
RESULTS: A total of 1649 stool tests were performed (mean 10.6 tests per patient). An infectious cause of diarrhea was found in 45 (28.8%) patients. Diagnostic yield was 6.2% for Clostridum difficile toxin assay, 12.9% for viral cultures, and 1.3% for rotavirus enzyme immunoassay. Bacterial cultures for enteric pathogens, examination for parasites, and rotavirus antigen assay combined had 0.5% positive yield.
CONCLUSIONS: Testing of multiple specimens per diarrheal episode did not increase diagnostic yield. The estimated cost savings by implementing single testing for each type of stool study per diarrheal episode was $49,764 annually (in 2001 US dollars). Judicious use of stool tests to evaluate diarrhea results in significant cost savings without compromising diagnostic yield.