HPV immunisation and increased uptake of cervical screening in Scottish women; observational study of routinely collected national data

To measure uptake of first invitation to cervical screening by vaccine status in population based cohort offered HPV immunisation in a national catch-up campaign by vaccination status. A retrospective observational study of routinely collected data from the Scottish Cervical Screening Programme (SCSP). Data was extracted and linked from the Scottish Cervical Call Recall System (SCCRS), the Scottish Population Register and the Scottish Index of Multiple Deprivation. Records from 201,023 women born between 1st January 1988 and 30th September 1993 were assessed. Women born in or after 1990 were eligible for the national catch-up programme of HPV immunisation. Attendance for screening was within 12 months of first invitation at age 20 years. Results: There was a significant decline in overall attendance from the 1988 cohort to the 1993 cohort with the adjusted odds of the 1988 cohort being 2.15 times (95% CI 2.07- 2.24) that of the 1993 cohort. Immunisation compensated for this decrease in uptake with unvaccinated individuals having a reduced odds of attendance compared to those fully vaccinated (OR=0.42, 95% CI 0.41-0.43). Not taking up the opportunity for HPV immunisation was associated with an attendance for screening below the trend line for all women before the availability of HPV immunisation. HPV immunisation is not associated with the reduced attendance for screening that had been feared. Immunised women in the catch-up cohorts appear to be more motivated to attend than unimmunised women but this may be a result of a greater awareness of health issues. These results, whilst reassuring, may not be reproduced in routinely immunised women. Continued monitoring of attendance for first smear and subsequent routine smears is needed.