Utility of Fecal Leukocyte Testing for Inpatients with Diarrhea

From the 2018 HVPAA National Conference

Jessica Barnes (University of Texas Southwestern Medical Center, Dallas, TX;), Kadam Patel (University of North Texas Health Sciences Center), Paul Southern (University of Texas Southwestern Medical Center, Dallas, TX;), Deepak Agrawal (University Texas Southwestern Medical Center)

Background

Fecal leukocyte (FL) testing is frequently ordered along with ova and parasites (O&P) and stool cultures for patients with diarrhea. FL are ordered with the notion that a positive test suggests bacterial diarrhea, clostridium difficile or inflammatory bowel disease. However, studies have questioned the clinical and diagnostic utility of FL.

Objectives

To determine the diagnostic utility of FL for inpatients and correlation of FL with positive stool cultures, O&P and Clostridium Difficile.

Methods

Retrospective analysis of all stool studies performed on patients in the emergency room and inpatients at a county hospital from December 2011 to February 2017. The sensitivity, specificity, positive predictive value (PPV), and likelihood ratio (LR) of FL testing was calculated for positive stool cultures, C Diff, and O&P. The results were also analyzed depending on FL test performed less or greater than 72 hours after admission.

Results

FL testing was performed 8,966 times and was positive in 327 (3.7%) cases. FL were ordered at the same time as stool cultures in 72% of patients and O&P in 60% of patients, suggesting reflex ordering of these tests. The sensitivity, specificity, PPV and positive likelihood ratio of FL testing in relation to stool cultures, C Diff and O&P, performed less than or greater than 72 hours since admission, are provided in Table 1. When FL testing was positive and other stool studies negative, the results were largely ignored suggesting clinical futility of the test. The costs associated with unnecessary FL was estimated to be about $3000/month (assuming $20/test)

Conclusion

Fecal leukocyte testing has low diagnostic and clinical utility as illustrated by its low diagnostic yield and poor correlation with other stool studies.  The use of this test should be questioned for evaluation of diarrhea in patients admitted to the hospital.

Implications for the Patient

Fecal leucocyte test does not contribute to patient care, is not recommended by guidelines and adds to costs of care. The use of this test should be restricted.