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Clostridium difficile Infections: Diagnosis, Treatment, and Prevention

Slide: 16 of 33

Comparative Effectiveness of Diagnostic Assays for C.difficile

The included studies used clinical stool specimens from patients suspected to have CDI. Also included were those studies that concurrently compared at least two diagnostic tests in the same laboratory using the same stool samples and using the same reference standard to reduce heterogeneity in the estimates. Studies must have used toxigenic culture, cell cytotoxicity assay, or combinations of tests as the reference test for toxigenic CDI. Direct comparisons of diagnostic tests without a reference test were not included. Studies that included patient outcomes or outcomes related to changes in therapy were identified. The results are presented in positive terms, that is, true positives (sensitivity) and false positives (1 minus specificity). Comparisons of diagnostic tests in terms of differences in their sensitivity (true positives for toxigenic C. difficile) and specificity (true negatives for toxigenic C. difficile) are provided as these statistics are the most relevant to clinical decisionmakers. Studies focus on the comparative diagnostic accuracy of commonly used rapid tests, such as immunoassays for C. difficile toxin and toxin gene detection tests, which may reduce the time lapse between the onset of symptoms and laboratory confirmation of CDI and treatment decisions. Repeat testing of selected specimens does not provide good comparative information about test accuracy and therefore is not covered in the focused review of diagnostic test accuracy.