Reproducibility of HPV DNA Testing by Hybrid Capture 2 in a Screening Setting Intralaboratory and Interlaboratory Quality Control in Seven Laboratories Participating in the Same Clinical Trial

Within a large Italian randomized trial on new technologies for cervical cancer screening involving 7 laboratories with different levels of experience, an intralaboratory and interlaboratory quality control program for human papillomavirus (HPV) DNA testing by Hybrid Capture 2 (HC2; Digene, Gaithersburg, MD) was implemented. To monitor the hybridization and detection steps, target samples containing purified, concentration-defined, HPV DNA were introduced in each test run. Only 3 of 1,024 showed a mistake in a positive vs negative classification with a 1 relative light unit (RLU)/positive control specimen (PC) ratio cutoff. To monitor the preanalytic steps (particularly denaturation), blinded specimens (33 collected in PreservCyt [Cytyc, Boxborough, MA] and 36 in Specimen Transport Medium. [STM, Digene]) were centrally prepared, divided into aliquots, and sent to each laboratory. The multiple-rater kappa scores for negative (< 1 RLU/PC), low-positive (1 to < 11 RLU/PC), and high-positive (>= 11 RLU/PC) samples, respectively, were 0.91, 0.60, and 0.69 with PreservCyt and 0.93, 0.87, and 0.90 with STM. Our data showed high reliability and reproducibility with HC2, with kappa values higher for STM than ThinPrep (Cytyc) samples.