Estimating the risk of developing CIN3 in HPV negative and in cytology and HPV double-negative women
The data of 4 randomised controlled trials (RCTs) comparing HPV-based to cytology-based cervical screened were pooled. All RCTs applied co-testing except NTCC phase 2. Women enrolled in such phase were excluded. In the cytology arm the cumulative incidence of CIN3 was computed for women with normal cytology at baseline. In the HPV arm the cumulative incidence of ICC was computed for women testing HPV negative at baseline and for women testing negative for both HPV and cytology at baseline.
Some 115756 women were included in the analysis. Among them 53348 were from the control arm and were cytology-negative at baseline while 62408 were from the experimental arm and were HPV negative at baseline. Of the latter 59065 were double negative to HPV and cytology, while 3343 had abnormal cytology. The cumulative incidence of CIN3 within 5.5 years from baseline was 241.5 per 105 py (95%CI 202.9-287.3) in the cytology arm when considering cytology-negative women, 115.0 (91.1-145.1) in the experimental arm when considering all HPV-negative women and 85.8 (65.0-113.1) in the experimental arm when considering double negative women.
The difference in future risk of developing CIN3 between double-negative and HPV- only negative women is small compared to that between HPV-negative and cytology-negative women.