To compare the performance of PapType, a bead-based full genotyping DNA assay for 14 high-risk (hr) and 2 low-risk (lr) HPV types, using two flow cytometer platforms - CytoFLEX and Attune.
Residual material from the PreservCyt samples of 6000 women attending for routine cervical screening sent to the cytology laboratory at St. Mary's Hospital, London were tested using PapType HPV test kit (Genera Biosystems, Scoresby, Victoria, Australia). The samples were run on CytoFlex (Beckman Coulter) and Attune Acoustic Focusing (Thermo Fisher Scientific) flow cytometer platforms following the manufacturer’s instructions. These samples were collected for the Predictors 3 Study1. The discordance between the platforms was analysed by hrHPV type. Comparisons were also made of sensitivity and specificity for CIN2+.
98.2% of cases gave an adequate result on Attune versus 99.1% on Cytoflex. Overall 17% of Attune cases were positive for at least 1 hrHPV type, and 21.1% of Cytoflex cases were positive for 1 or more hrHPV type. Overall agreement between Attune and Cytoflex was good for detecting hrHPV types (kappa 72.4, 95% CI (70.1, 74.6)). Cytoflex called more cases positive than Attune (significant difference for HPV types 16, 18, 45, 52, 58, 66 and 68). Attune had statistically significantly more positives for HPV 59. There was a wide range of agreement for individual HPV types (kappa 41.1 for HPV 18 to kappa 92.1 for HPV 33). Overall for CIN2+ cases only 1 case was discordant (positive for Cytoflex, negative for Attune). CIN2+ sensitivity was higher for CytoFlex (97.5 vs 95.0). Specificity was higher for Attune (<CIN2 83.5% vs 79.4%).
These preliminary data suggest that both Attune and CytoFlex are reliable flow cytometry platforms on which to run the PapType test. Further HPV type specific and signal strength data will be presented in the final analyses.
1 Cuzick J, Cadman L, Mesher D, Austin J, Ashdown-Barr L, Ho L, Terry G, Liddle S, Wright C, Lyons D, Szarewski A Comparing the performance of six human papillomavirus tests in a screening population. Br J Cancer. 2013 Mar 5;108(4):908-13.