The diagnostic performance of the scent dogs in the triple-blind validation test
| Dog | Dogs’ indication | Sniffed RT-PCR positive samples | Sniffed RT-PCR negative samples | Sniffed samples/all presented samples | Sniffed samples (% from all samples) | Sesniff* (95 % CI) | Spsniff† (95 % CI) | PPVsniff‡ (95% CI) | NPVsniff§ (95 % CI) | Seall¶ (95% CI) | Spall
10
(95% CI) |
| Silja | Positive Negative | 998 | 11 206 | 107/114 217/306 | 324 (77) | 93% (85% to 96%) | 95% (91% to 97%) | 90% (82% to 95%) | 96% (92% to 98%) | 87% (79% to 92%) | 96% (93% to 98%) |
| Rele | Positive Negative | 1047 | 18 197 | 111/114 215/306 | 326 (78) | 94% (87% to 97%) | 92% (87% to 95%) | 85% (77% to 91%) | 97% (93% to 98%) | 91% (84% to 95%) | 94% (91% to 96%) |
| Kosti | Positive Negative | 998 | 23 203 | 107/114 226/306 | 333 (79) | 93% (85% to 96%) | 90% (85% to 93%) | 81% (73% to 87%) | 96% (92% to 98%) | 87% (79% to 92%) | 92% (89% to 95%) |
| E.T. | Positive Negative | 90 12 | 23 201 | 102/114 224/306 | 326 (78) | 88% (80% to 94%) | 90% (85% to 93%) | 80% (71% to 86%) | 94% (90% to 97%) | 79% (70% to 86%) | 92% (89% to 95%) |
| All dogs | Positive Negative | 392 35 | 75 807 | 427/456 882/1224 | 1309 (78) | 92% (89% to 94%) | 91% (89% to 93%) | 84% (81% to 87%) | 96% (94% to 97%) | 86% (82% to 89%) | 94% (92% to 95%) |
*Sesniff, sensitivity on sniffed samples only.
†Spsniff, specificity on sniffed samples only.
‡PPVsniff, positive predictive value on sniffed samples. Based on the prevalance rate of COVID-19 positive samples in our data (27%).
§NPVsniff, negative predictive value on sniffed samples: Based on the prevalence rate of COVID-19 positive samples in our data (27%).
¶Seall, sensitivity on all randomised samples: 10. Spall, specificity on all randomised samples.
RT-PCR, reverse transcriptase-polymerase chain reaction.