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Table 7 Gene-protein IHC/BISH (comparator) vs. single IHC/BISH (reference) agreement analyses

From: A gene-protein assay for human epidermal growth factor receptor 2 (HER2): brightfield tricolor visualization of HER2 protein, the HER2 gene, and chromosome 17 centromere (CEN17) in formalin-fixed, paraffin-embedded breast cancer tissue sections

Single IHC/BISH assay
  Gene-protein IHC/BISH Positive Negative Total
Reader A Positive 50 2 52
  Negative 1 112 113
  Total 51 114 165
  PPA: n/N (%) (95% CI) 50/51 (98.0) (89.7–99.7)   
  NPA: n/N (%) (95% CI) 112/114 (98.2) (93.8–99.5)   
  OPA: n/N (%) (95% CI) 162/165 (98.2) (94.8–99.4)   
  Kappa coefficient (95% CI) 0.96 (0.91–1.00)   
Reader B Positive 50 2 52
  Negative 3 117 120
  Total 53 119 172
  PPA: n/N (%) (95% CI) 50/53 (94.3) (84.6–98.1)   
  NPA: n/N (%) (95% CI) 117/119 (98.3) (94.1–99.5)   
  OPA: n/N (%) (95% CI) 167/172 (97.1) (93.4–98.8)   
  Kappa coefficient (95% CI) 0.93 (0.87–0.99)   
Reader C Positive 52 3 55
  Negative 2 116 118
  Total 54 119 173
  PPA: n/N (%) (95% CI) 52/54 (96.3) (87.5–99.0)   
  NPA: n/N (%) (95% CI) 116/119 (97.5) (92.8–99.1)   
  OPA: n/N (%) (95% CI) 168/173 (97.1) (93.4–98.8)   
  Kappa coefficient (95% CI) 0.93 (0.88–0.99)   
  1. IHC: immunohistochemistry; BISH: brightfield in situ hybridization; PPA: positive percent agreement; NPA: negative percent agreement; OPA: overall percent agreement.
  2. Note: IHC/BISH status: positive = IHC is positive or BISH is amplified; negative = IHC is negative and BISH is non-amplified.