Human papillomavirus (HPV) testing by the Cobas 4800 HPV test as primary screening for cervical cancer is currently being implemented in Norway in a randomized controlled fashion. To confirm satisfactory HPV test reliability, an evaluation of inter-laboratory reproducibility between the laboratories involved in the implementation was initiated.
The Cobas HPV test simultaneously detects 14 high-risk types, including individual genotype of HPV16 and HPV18. In addition to the three laboratories involved in the implementation, the Norwegian HPV reference laboratory was included as a fourth comparative laboratory. A stratified sample of 500 cervical LBC samples was used in the evaluation, with an aim towards a high-risk HPV positivity of ~25%. Samples were collected at one laboratory, anonymized, aliquoted, and distributed to the other laboratories.
Considering all specimens, there was a 95.6% overall agreement, an 86.3% positive agreement, and a kappa value of 0.94 (95% CI 0.92-0.97). For negative cytology specimens, there was a 95.8% overall agreement, a 67.4% positive agreement, and a kappa value of 0.88 (95% CI 0.80-0.93). For abnormal cytology specimens, there was a 95.8% overall agreement, a 95.5% positive agreement, and a kappa value of 0.86 (95% CI 0.71-0.97). Ranking the test results according to cancer risk, there was a 94.4% overall agreement, an 82.5% positive agreement, and a kappa value of 0.94 (95% CI 0.91-0.96).
The study showed a high inter-laboratory reproducibility of HPV testing by the Cobas 4800 HPV test, implying satisfactory user performance and reliability in the laboratories involved in the implementation project.