title: HPV immunisation and cervical screening--confirmation of changed performance of cytology as a screening test in immunised women: a retrospective population-based cohort study.
abstract: BACKGROUND
  To document the effect of bivalent HPV immunisation on cervical cytology as a screening test and assess the implications of any change, using a retrospective analysis of routinely collected data from the Scottish Cervical Screening Programme (SCSP).
  
  
  METHODS
  Data were extracted from the Scottish Cervical Call Recall System (SCCRS), the Scottish Population Register and the Scottish Index of Multiple Deprivation. A total of 95 876 cytology records with 2226 linked histology records from women born between 1 January 1988 and 30 September 1993 were assessed. Women born in or after 1990 were eligible for the national catch-up programme of HPV immunisation. The performance of cervical cytology as a screening test was evaluated using the key performance indicators used routinely in the English and Scottish Cervical Screening Programmes (NHSCSP and SCSP), and related to vaccination status.
  
  
  RESULTS
  Significant reductions in positive predictive value (16%) and abnormal predictive value (63%) for CIN2+ and the mean colposcopy score (18%) were observed. A significant increase (38%) in the number of women who had to be referred to colposcopy to detect one case of CIN2+ was shown. The negative predictive value of negative- or low-grade cytology for CIN2+ increased significantly (12%). Sensitivity and specificity, as used by the UK cervical screening programmes, were maintained.
  
  
  CONCLUSIONS
  The lower incidence of disease in vaccinated women alters the key performance indicators of cervical cytology used to monitor the quality of the screening programme. These findings have implications for screening, colposcopy referral criteria, colposcopy practice and histology reporting.
authors.affiliation: Department of Pathology, University of Edinburgh, EH16 4SA, Scotland.
authors.forename: T J
authors.initials: TJ
authors.lastname: Palmer
authors.affiliation: Information Services Division, NHS National Services Scotland, Gyle Square, Edinburgh EH12 9EB, Scotland.
authors.forename: M
authors.initials: M
authors.lastname: McFadden
authors.affiliation: Health Protection Scotland, Glasgow G2 6QE, Scotland.
authors.forename: K G J
authors.initials: KG
authors.lastname: Pollock
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, Glasgow G1 1XH, Scotland.
authors.forename: K
authors.initials: K
authors.lastname: Kavanagh
authors.affiliation: Scottish Human Papillomavirus Reference Laboratory, Royal Infirmary of Edinburgh, Edinburgh EH16 4SA, Scotland.
authors.forename: K
authors.initials: K
authors.lastname: Cuschieri
authors.affiliation: University of Aberdeen, Aberdeen AB25 2ZD, Scotland.
authors.forename: M
authors.initials: M
authors.lastname: Cruickshank
authors.affiliation: University of Aberdeen, Aberdeen AB25 2ZD, Scotland.
authors.forename: S
authors.initials: S
authors.lastname: Cotton
authors.affiliation: Department of Cytology, Ninewells Hospital, Dundee DD1 9SY, Scotland.
authors.forename: S
authors.initials: S
authors.lastname: Nicoll
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, Glasgow G1 1XH, Scotland.
authors.forename: C
authors.initials: C
authors.lastname: Robertson
mesh_terms: D015331:Cohort Studies; D003127:Colposcopy; D003581:Cytodiagnosis; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D065006:Papanicolaou Test; D030361:Papillomavirus Infections / Q000517:prevention & control*; D053918:Papillomavirus Vaccines / Q000627:therapeutic use*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012606:Scotland; D012680:Sensitivity and Specificity; D065310:Squamous Intraepithelial Lesions of the Cervix / Q000175:diagnosis / Q000473:pathology* / Q000517:prevention & control; D006113:United Kingdom; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000517:prevention & control; D014626:Vaginal Smears; D055815:Young Adult; D002578:Uterine Cervical Dysplasia / Q000175:diagnosis / Q000473:pathology* / Q000517:prevention & control
chemical_list: D053918:Papillomavirus Vaccines