Table 1.
Performance of the Alfred 60/AST device at various detection thresholdsa
| Alfred 60 device cutoff (CFU/ml) |
n (%)b |
% |
|||||
|---|---|---|---|---|---|---|---|
| FP | FN | SN | SP | PPV | NPV | Reduction in culturing | |
| 800 | 71 (14.0) | 9 (1.8) | 88.8 | 83.4 | 50.0 | 97.5 | 72.0 |
| 1,000 | 66 (13.0) | 11 (2.2) | 86.3 | 84.6 | 51.1 | 97.1 | 73.4 |
| 2,000 | 60 (11.8) | 11 (2.2) | 86.3 | 86.0 | 53.5 | 97.1 | 74.6 |
| 5,000 | 55 (10.8) | 12 (2.4) | 85.0 | 87.1 | 55.3 | 96.9 | 75.8 |
| 15,000 | 37 (7.3) | 16 (3.1) | 80.0 | 91.4 | 63.4 | 96.1 | 80.1 |
| 30,000 | 32 (6.3) | 23 (4.5) | 71.3 | 92.5 | 64.0 | 94.5 | 82.5 |
| 100,000 | 23 (4.5) | 27 (5.3) | 66.3 | 94.6 | 69.7 | 93.8 | 85.0 |
a
Abbreviations: FP, false positive; FN, false negative; SN, sensitivity; SP, specificity; PPV, positive predictive value; NPV, negative predictive value.
b
Total number of samples was 508.