OBJECTIVETo validate the conversion factor (CF) for the conversion of BCR-ABL (P210) transcript levels to the international scale in chronic myeloid leukemia (CML).

METHODSIn 2012, the international reference laboratory in Adelaide, Australia (IMVS) sent two batches of RNA samples, 30 samples per batch, to Peking University People's Hospital (PKUPH). By comparing BCRABL (P210) transcript levels reported by the two laboratories, CF of PKUPH was calculated and validated by IMVS. In 2013, PKUPH prepared the exchange samples for validation of CF of 9 hospitals who have calculated CFs before. The fresh BCR-ABL (P210) (+) cells were serially diluted by BCR-ABL (P210) (-) cells to prepare 22 kinds of samples with different BCR-ABL transcript levels, each kind had 10 parallel samples. Trizol reagent was added in each tube. Ten hospitals tested BCR-ABL transcript levels of one set of 22 samples. Agreement between BCR-ABL transcript levels of each laboratory and PKUPH was assessed by the Bland-Altman method.

RESULTSPKUPH successfully validated its CF with bias 1.1 fold and 95% limits of agreement between -4.7 and 4.9 fold. Of 9 hospitals whose validation performed by sample exchanges with PKUPH, 6 hospitals successfully validated their CF with bias ≤±1.4 fold and 95% limits of agreement within ±6 fold.

CONCLUSIONValidation of CF examined the stability of the detection of BCR-ABL (P210) transcript levels, which was necessary for the valid conversion of BCR-ABL (P210) transcript levels to the international scale in CML.