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Journal List > J Gen Intern Med > v.12(1); Jan 1997

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J Gen Intern Med. 1997 January; 12(1): 57–62.
doi: 10.1046/j.1525-1497.1997.12108.x.
PMCID: PMC1497057
Copyright 1997 by the Society of General Internal Medicine
Predicting Clostridium difficile Stool Cytotoxin Results in Hospitalized Patients with Diarrhea
David A Katz, MD, MSc,1 David W Bates, MD, MSc,3 Eve Rittenberg, MA,3 Andrew Onderdonk, PhD,4 Kenneth Sands, MD,5 Laurie A Barefoot, RN,2 and David Snydman, MD2
1Received from the Division of Clinical Decision Making, Department of Medicine, New England Medical Center and Tufts University School of Medicine, Boston, Mass.
2The Division of Infectious Diseases, Department of Medicine, New England Medical Center and Tufts University School of Medicine, Boston, Mass.
3The Division of General Internal Medicine and Primary Care, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Mass.
4The Division of Microbiology, Brigham and Women’s Hospital and Harvard Medical School, Boston, Mass.
5The Division of Infectious Diseases, Beth Israel Hospital and Harvard Medical School, Boston, Mass.
Presented at the Society of General Internal Medicine 18th annual meeting, San Diego, Calif., May 4–6, 1995.
Supported in part by research grant RO1-HS07107-02 from the Agency for Health Care Policy and Research. Dr. Katz was supported by a National Library of Medicine research fellowship at the time of this work.
Address correspondence and reprint requests to Dr. Katz: Section of General Internal Medicine, Suite 100, 2870 University Ave., Madison, WI 53705.
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Abstract
OBJECTIVE
To validate a model for the prediction of Clostridium difficile cytotoxin assay results, and to identify a subgroup of patients with a very low likelihood of C. difficile–associated disease in whom the yield of routine cytotoxin testing is low.
DESIGN
Prospective cohort study. Relevant clinical symptoms, signs, and antibiotic exposure were recorded before reporting of assay results. Each predictor was assigned a score based on regression coefficients, and patients were stratified according to their total score.
SETTING
Two urban, tertiary care, university hospitals.
PATIENTS
A total of 609 consecutive adult inpatients who received testing for C. difficile cytotoxin during a 3-month period in 1994.
MEASUREMENTS AND MAIN RESULTS
The prevalence of positive cytotoxin assays was 8% in the validation set, compared with 14% in the derivation set. Defining patients without both prior antibiotic use and at least one symptom predictor (significant diarrhea or abdominal pain) as a low-risk subgroup, the misclassification rate was 2.8% (5/177) for assay results; of the five misclassified cases patients, only one was judged to have C. difficile–associated disease. Use of this rule to identify low-risk patients could have potentially averted 29% of all cytotoxin assays.
CONCLUSIONS
Patients without a history of antibiotic use and either significant diarrhea or abdominal pain are unlikely to have positive C. difficile cytotoxin assays and may not require cytotoxin testing.
Keywords: Clostridium difficile, routine diagnostic tests, quality of care, utilization
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