Table 2.
Concordance of two EGFR mutation tests in tumor tissue and plasma samples.
| Test Results | Tumor Tissue | Plasma |
|---|---|---|
| (Reference: cobas v2) | (n = 217) | (n = 201) |
| Concordant Results | ||
| Both Wild | 123 (57%) | 165 (82%) |
| Both Mutant | 75 (35%) | 21 (10%) |
| E x19 del | 17 (8.5%) | 11 (5.5%) |
| L858R | 14 (6.5%) | 3 (1.4%) |
| T790M | 1 (0.5%) | 2 (1.0%) |
| L858R+T790M | 30 (14%) | 3 (1.5%) |
| Ex19 del+T790M | 13 (6.0%) | 2 (1.0%) |
| Discordant Result | ||
| P_Mutant/c_Wild a | 14 (6.5%) | 7 (3.5%) |
| c_Mutant/P_Wild b | 1 (0.5%) | 6 (3.0%) |
| Different Mutant | 4 (1.8%) | 2 (1.0%) |
| Test Evaluation | ||
| Sensitivity (PPA) c (95% CI) | 94% (86%–97%) | 72% (54%–85%) |
| Specificity (NPA) c (95% CI) | 90% (84%–94%) | 96% (92%–98%) |
| Accuracy (OPA) c (95% CI) | 91% (87%–94%) | 93% (88%–95%) |
| Kappa Coefficient (95% CI) | 0.82 (0.74–0.92) | 0.69 (0.54–0.84) |
a P_Mutant/c_Wild: PANAMutyper result is mutant but cobas v2 result is wild; b c_Mutant/P_Wild: cobas v2 result is mutant but PANAMutyper result is wild; c Calculation with cobas v2 as reference; EGFR, epidermal growth factor receptor; OPA, overall percentage agreement; PPA, positive percentage agreement; NPA, negative percentage agreement.