A comparability study of 5 commercial KRAS tests

Diagnostic Pathology

Table 3 Comparability of KRAS Mutational Analysis Using the κ Statistic

κ (95% CI) [n]*	Allele-Specific PCR (HistoGeneX/DxS)	Direct Sequencing (Gentris)	Allele-Specific Hybridization (Invitek)	Allele-Specific PCR Extensions (Genzyme)	Picotiter Plate Sequencing (Agencourt)
Direct sequencing (Amgen)	0.95 (0.85, 1.00) [40]	0.75 (0.52, 0.98) [32]	0.13 (–0.15, 0.42) [27]	0.94 (0.83, 1.00) [35]	0.94 (0.82, 1.00) [32]
Allele-specific PCR (HistoGeneX/DxS)		0.75 (0.52, 0.98) [32]	0.11 (–0.16, 0.37) [27]	0.89 (0.73, 1.00) [35]	0.88 (0.71, 1.00) [32]
Direct sequencing (Gentris)	0.75 (0.52, 0.98) [32]		–0.09 (–0.27, 0.08) [21]	0.74 (0.51, 0.98) [31]	0.63 (0.35, 0.92) [27]
Allele-specific hybridization (Invitek)	0.11 (–0.16, 0.37) [27]	–0.09(–0.27, 0.08) [21]		–0.08(–0.22, 0.06) [25]	0.29 (–0.05, 0.63) [21]
Allele-specific PCR extensions (Genzyme)	0.89 (0.73, 1.00) [35]	0.74 (0.51, 0.98) [31]	–0.08(–0.22, 0.06) [25]		1.00 (1.00, 1.00) [28]
Picotiter plate sequencing (Agencourt)	0.88 (0.71, 1.00) [32]	0.63 (0.35, 0.92) [27]	0.29 (–0.05, 0.63) [21]	1.00 (1.00, 1.00) [28]

PCR = polymerase chain reaction.
*The κ statistic [10] measures agreement for KRAS mutational status (wild type vs mutant), with a value of 1.0 indicating perfect agreement and a value of -1.0 indicating perfect disagreement. Values in brackets are the 95% CI for the κ statistic. Values in square brackets indicate the number of samples being compared by the κ statistic (ie, the number of samples for which the 2 assays being compared both had a determination of wild-type or mutant).

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