Comparison of Droplet Digital PCR versus qPCR Measurements on the International Scale for the Molecular Monitoring of Chronic Myeloid Leukemia Patients

Background BCR - ABL1/ABL1 p210 measurement by quantitative polymerase chain reaction (qPCR) is used worldwide to monitor the molecular response in chronic myeloid leukemia (CML) patients. Droplet digital polymerase chain reaction (ddPCR) seems to show a greater sensitivity than qPCR, probably due to the high number of replicates analyzed in ddPCR for the comparison. Additionally, in a recently published comparison, ddPCR measurements were not adequately transformed into International Scale (IS). Method We have analyzed 50 CML patients and ten non-CML donors in parallel by qPCR and ddPCR. To the best of our knowledge, this is the first study comparing both techniques under similar conditions, with BCR - ABL1/ABL1 measurements performed via both techniques transformed into IS. Results Qualitative and quantitative comparisons showed excellent results. The qualitative correlation showed a Kappa index of 0.94 (95% confidence interval [CI] 0.90–0.98) ( P