The impact of HPV type on colposcopy performance in women offered HPV immunisation in a catch-up vaccine programme: a two centre observational study

Objective
To determine if HPV immunisation has affected the prevalence of HPV genotypes and colposcopic features of CIN in young women referred for colposcopy.

Design
A two-centre observational study including vaccinated and unvaccinated women.

Setting
Colposcopy clinics serving two health regions in Scotland, UK.

Population
361 women aged 20-25 years attending colposcopy following an abnormal cervical cytology result at routine cervical screening.

Methods
Cervical samples were obtained from women for HPV DNA genotyping and mRNA E6/E7 expression of HPV 16,18,31,33 and 45. Demographic data, cytology and histology results and colposcopic features were recorded. Chi squared analysis was conducted to identify associations between vaccine status, HPV genotypes and colposcopic features.

Main outcome measures
Colposcopic features, HPV genotypes, mRNA expression and cervical histology.

Results
The prevalence of HPV 16 was significantly lower in the vaccinated (8.6%) compared with the unvaccinated (46.7%) group (p=0.001). The number of cases of cervical intraepithelial neoplasia 2 or more (CIN2+) was significantly lower in vaccinated women (p=0.006).HPV vaccine did not have a statistically significant effect on commonly recognised colposcopic features but there was a slight reduction in the positive predictive value (PPV) of colposcopy for CIN2+ from 74% (unvaccinated) to 66.7% (vaccinated).

Conclusions
In this group of young women with abnormal cytology referred to colposcopy, HPV vaccination via a catch-up programme reduced the prevalence of CIN2+ and HPV 16 infection. The reduced PPV of colposcopy for the detection of CIN2+ in vaccinated women is at the lower acceptable level of the UK national cervical screening programme guidelines.