Table 2.
Testing approach | Average cost/test ($) | Sensitivity of test/algorithm (%)⁎ | No. of patients positive for CDI missed | Specificity of test/algorithm (%)⁎ | No. of false-positive test results | Patients in isolation with CDI | Patients in isolation without CDI | Patients with CDI not in isolation |
---|---|---|---|---|---|---|---|---|
GDH or EIA alone | 18.00 | 55 | 45 | 94 | 54 | Days 1–5, 55 | Days 1–5, 54 | Days 1–5, 45 |
Reflex to NAAT for GDH+ and EIA- | 19.12 | 85 | 15 | 93.9 | 55 | Day 1, 55; days 2–5, 85 | Day 1, 54; days 2–5, 55 | Day 1, 45; days 2–5, 15 |
Reflex to toxigenic culture for GDH+ and EIA- | 18.51 | 86 | 14 | 93.9 | 55 | Days 1–4, 55; day 5, 86 | Days 1–4, 54; day 5, 55 | Days 1–4, 45; day 5, 14 |
Reflex to direct cytotoxin for GDH+ and EIA- | 18.32 | 77 | 23 | 93.9 | 55 | Days 1–2, 55; days 3–5, 77 | Days 1–2, 54; days 3–5, 55 | Days 1–2, 45; days 3–5, 23 |
NAAT alone | 35.00 | 95 | 5 | 96 | 36 | Days 1–5, 95 | Days 1–5, 36 | Days 1–5, 5 |
Assumptions: 1000 patients tested with each test or algorithm; 10% prevalence (ie, 100 true-positive patients and 900 true-negative patients); GDH-positive and EIA-negative samples = 32, which will be retested using one of the reflex methods; testing on first shift of each day; one test type is performed per day; no pre-emptive isolation if test results are reported on same day as ordered (ie, <8-hour turnaround time); pre-emptive isolation for CDI orders includes time for other tests; isolation continues until the day the test result is negative; assumes a 5-day length of stay.
Sensitivity and specificity values are based on published literature.2–5,7–10,26–30,32–37,44–48,53–56,58–61