Table 2.
Performance Characteristics of Culture-Independent Diagnostic Tests for Candidemia as Compared With Culture as the Imperfect Reference Standard
| Prevalence | Corresponding Patient Populations | Beta-D-Glucan (60%/80%) |
Beta-D-Glucan (80%/80%) | PCR, T2Candida (70%/90%) |
PCR, T2Candida (90%/90%) | ||||
|---|---|---|---|---|---|---|---|---|---|
| PPV, % | NPV, % | PPV, % | NPV, % | PPV, % | NPV, % | PPV, % | NPV, % | ||
| ~0.4% | Any patient for whom a blood culture is collected | 1 | 99.8 | 1 | 99.9 | 3 | 99.8 |
3 | >99.9 |
| ~1% | Patient in ICU with fever | 3 | 99.5 | 4 | 99.7 | 7 | 99.7 | 8 | 99.9 |
| ~3% | Patients with sepsis, septic shock, in ICU for >3–7 d |
8.5 | 98.5 | 11 | 99.2 | 18 | 99 | 22 | 99.6 |
| ~10% | ICU patient at increased risk for candidemia based on clinical prediction score |
25 | 94.7 | 31 | 97 | 44 | 96 | 50 | 98.8 |
Table 2 adapted from Clancy and Nguyen [34]. BDG sensitivity/specificity for diagnosing candidemia are taken from meta-analyses cited in the text. PCR and T2Candida sensitivity/specificity for diagnosing candidemia are taken from a meta-analysis and DIRECT and DIRECT2 clinical trials [40, 42, 43]. In order to make rational use of culture-independent diagnostic tests, clinicians must be familiar with test performance and prevalence of various types of invasive candidiasis locally.
Culture-independent diagnostic test–guided patient management strategies have not been validated in clinical trials. We propose that patient populations with PPV >15% might be targeted for such trials to better identify the clinical benefit of response to antifungal therapy. These “false positives” among high-risk patient populations may represent deep-seated invasive candidiasis that is negative by blood and other cultures.
Abbreviations: BDG: 1,3-beta-D-glucan; ICU, intensive care unit; NPV, negative predictive value; PCR, Candida polymerase chain reaction; PPV, positive predictive value.