TABLE 2.
Comparison of Gram and Wayson stain results with culture resultsa
| Stain(s) and observer | Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | J index |
|---|---|---|---|---|---|
| Gramb | |||||
| 1 | 52.5 | 66.3 | 40.4 | 76.3 | 0.19 |
| 2 | 62.5 | 71.7 | 49.0 | 81.5 | 0.34 |
| 3 | 47.5 | 73.9 | 44.2 | 76.4 | 0.21 |
| Mean | 54.2 | 70.6 | 44.5 | 78.1 | 0.25 |
| Wayson | |||||
| 1 | 47.5 | 68.5 | 39.6 | 75 | 0.16 |
| 2 | 37.5 | 77.2 | 41.7 | 74 | 0.15 |
| 3 | 32.5 | 85.9 | 50 | 74.5 | 0.18 |
| Mean | 39.2 | 77.2 | 43.8 | 74.5 | 0.16 |
| Wayson and Gram combinedc | |||||
| 1 | 47.5 | 64.1 | 36.5 | 73.8 | 0.12 |
| 2 | 57.5 | 72.8 | 47.9 | 79.8 | 0.30 |
| 3 | 45 | 78.3 | 47.4 | 76.6 | 0.23 |
| Mean | 50.0 | 71.7 | 43.9 | 76.7 | 0.22 |
a
PPV, positive predictive value; NPV, negative predictive value.
b
Any gram-negative rods seen.
c
Either or both stains positive for bipolar rods.