SAN FRANCISCO – A side-by-side comparison of three bedside tools used to identify severe cases of Clostridium difficile infection yielded no clear winner, a reminder that judgment at diagnosis is still the clinician’s best bet.
Criteria from the Infectious Diseases Society of America were more sensitive but the least specific than both the Hines Veterans Affairs (VA) and the ATLAS severity scoring systems, Thien-Ly Doan, Pharm.D. explained in an interview at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
Sherry E. Boschert/IMNG Medical Media
Thien-Ly Doan, Pharm.D.
The Hines VA system for stratifying patients missed 19 of 44 severe/complicated cases of C. difficile infection. The ATLAS scoring system (which incorporates five parameters: age, temperature, leukocytosis, albumin, and systemic concomitant antibiotic use) missed 14 of the 44 cases in a retrospective chart review of 109 patients hospitalized for more than a day with confirmed C. difficile infection.
The IDSA guidelines missed only 5 of the 44 severe/complicated infections, but they cast such a wide net that anyone with a white count above 15,000 cells/mm3 or an elevated creatinine (1.5 times or greater than the premorbid level) is considered to have severe C. difficile infection, she said.
Use of the IDSA guidelines could increase unnecessary use of vancomycin instead of metronidazole, said Dr. Doan, a clinical coordinator at Long Island Jewish Medical Center, New Hyde Park, N.Y.
The IDSA criteria suggested that nearly 60% of the 109 patients had severe infection. However, the 44 severe/complicated C. difficile patients comprised just 40% of the study population. They were defined in the study as patients who were in critical care or whose infections were refractory to treatment and who had ileus, severe pancolitis/toxic megacolon, a WBC of 15,000 cells/mL with hypotension, surgery related to C. difficile infection, or who had died from infection.
Dr. Doan and her associates compared the three stratification systems in evaluating the charts of adults with C. difficile infection at the medical center, who had a mean age of 71 years. A total of 74% of patients were on the medicine service, 22% were in critical care, and 4% were on the surgical service; 34% were female.
The Centers for Disease Control and Prevention also offer severity criteria, but these require the observation of clinical end points and thus are ineffective for assessing patients at initial presentation, she said in a poster presentation at the meeting, sponsored by the American Society for Microbiology.
The Hines VA scoring system, in addition to missing the most severe cases, also gives a great deal of weight to diagnostic imaging, which "makes it impractical at our institution," she said. The Hines VA tool incorporates temperature, the presence of ileus, systolic blood pressure, leukocytosis, and abnormal CT findings to stratify patients by severity.
"We’re going to continue relying on the clinician’s assessment at the bedside at the time of diagnosis to evaluate whether cases are severe or not severe, and not use any of these tools that are available," Dr. Doan said.
A good bedside tool sure would be nice, though, to have a good, objective way of identifying severe C. difficile infection, she added. In a large health system, order sets could be developed based on the tool’s findings "so that everybody would be on the same page in terms of treatment," she said. None of the current tools are good enough for that.
Severe cases of C. difficile are on the rise because of increasing prevalence of the hypervirulent NAP1/BI/027 strain, she noted.
A number of clinicians at the meeting approached her with their own versions of bedside tools for identifying severe C. difficile infection, which Dr. Doan and her associates may evaluate next. They also may compare the tools on different subpopulations of patients with severe infection, such as only patients whose death or surgery was related to C. difficile infection.
Dr. Doan reported having no financial disclosures.