Table 1.
Results of the dilution test compared to gold standard (N = 495)
| Dilution | Result | Number | Number with gold standard result | Concordance | Kappa value* | |
|---|---|---|---|---|---|---|
| Positive (%) | Negative (%) | |||||
| 1/10 | Positive | 259 | 247 (95.3) | 12 (4.6) | 97.6 | 0.952 |
| Negative | 236 | 0 | 236 (100) | |||
| 1/40 | Positive | 249 | 247 (99.2) | 2 (0.8) | 99.6 | 0.992 |
| Negative | 246 | 0 | 246 (100) | |||
| 1/160 | Positive | 246 | 246 (100) | 0 | 99.8 | 0.996 |
| Negative | 249 | 1 (0.4) | 248 (99.6) | |||
| 1/640 | Positive | 244 | 244 (100) | 0 | 99.4 | 0.988 |
| Negative | 251 | 3 (1.2) | 248 (98.8) | |||
| 1/2560 | Positive | 240 | 240 (100) | 0 | 98.6 | 0.972 |
| Negative | 255 | 7 (2.8) | 248 (97.2) | |||
| 1/10,240 | Positive | 221 | 221 (100) | 0 | 94.8 | 0.895 |
| Negative | 274 | 26 (9.5) | 248 (90.5) | |||
| TOTAL | 495 | 247 (49.9) | 248 (50.1) | |||
*All p values for the kappa statistics are <0.001