Background: Most cervical cancers are associated with human papillomavirus (HPV) types 16 and 18. In 2008, New Zealand commenced a quadrivalent HPV (virus-like particles of types 6, 11, 16 and 18) vaccination programme.
Aim: Document trends in number of colposcopy referrals and number and grade of cervical abnormalities diagnosed in women (20-24 years) referred to three large colposcopy clinics over time.
Method: Retrospective analysis of colposcopy clinic data.
Results: The dataset included 5,012 episodes from 4,682 women. In Auckland (2013-2017), there was a 38% decrease in colposcopy referrals and 55% decrease in cervical intraepithelial neoplasia grade 2 (CIN2) or worse diagnoses. In Waikato (2011-2017), there was an 8% decrease in referrals and 22% reduction in CIN2 or worse diagnoses. In Canterbury (2011-2017), there was a 24% decrease in referrals and 49% reduction in CIN2 or worse diagnoses. Across all centres, the decrease in cervical intraepithelial neoplasia grade 3 (CIN3) or worse diagnoses was marked and more consistent than in CIN2 diagnoses. However, while the proportion of biopsies reported as CIN3 or worse decreased in non-Māori (24% in 2013 vs 16% in 2017, nptrend z=-4.24, p>|z| <.001), there was no change in Māori women (31% in 2013 vs 29% in 2017, nptrend z=-0.12, p>|z| =.90).
Conclusions: We observed a decreased number of CIN diagnoses in young women over time, with a particularly large drop in the number of CIN3/AIS/CGIN diagnoses. However, compared to non-Māori, Māori women having biopsies are more likely to have CIN3 or worse and there was a smaller reduction in the total number of Māori women diagnosed with CIN2 or worse.