Objective: To present performance indicators from the second round of the Vallecamonica-Sebino HPV screening programme in women who had tested negative about four years earlier (mean 45 months).
Methods: From 2010 to 2012, the target female population (aged 25-64) was invited to the first HPV screening round. In 2013-2017, women were rescreened for the second round. HPV-negative women at the first round were initially rescreened after three years. The interval was gradually increased to five years. HPV-positive women underwent cytology triage: positives were referred to colposcopy and negatives to repeat testing after one year. If HPV was persistently positive, women were referred to colposcopy, if negative, to normal interval rescreening.
Results: In the second round, of 13,824 previously HPV-negative women, 598 were HPV-positive (4.3%), of whom 297 were positive at cytology triage. Of those referred to one-year HPV test, 291 complied (98.0%), 133 (50.2%) of whom were persistently positive. Total referral was 3.1% compared with 6.6% in the first round (age-adjusted relative referral 0.59, 95% CI: 0.53-0.65). There were 24 cervical intraepithelial neoplasia 2+ (three cervical intraepithelial neoplasia 3+). Detection was 0.17%, compared with 0.9% in the first round. Age-adjusted relative detections were 0.25 (95% CI: 0.16-0.39) and 0.18 (95% CI: 0.05-0.61) for cervical intraepithelial neoplasia 2+ and cervical intraepithelial neoplasia 3+, respectively. Positive predictive value was 5.7%, compared with 14.6% in the first round.
Conclusions: At second round, referral was half that at first round, while cervical intraepithelial neoplasia 2+ detection decreased nine-fold. Consequently, positive predictive value decreased dramatically. Rescreening four years after an HPV-negative test makes the process inefficient due to the low prevalence of lesions.
Keywords: HPV DNA test; Human papilloma virus; cervical cancer; cervical intraepithelial neoplasia; mass screening.