Long-term adherence to follow-up after treatment of cervical intraepithelial neoplasia: nationwide population-based study

OBJECTIVE: To measure adherence to annual follow-up among women treated for cervical intraepithelial neoplasia.

DESIGN: Prospective, population-based, register study.

SETTING: Denmark, 1996-2007.

POPULATION: All women treated for cervical intraepithelial neoplasia with conization.

METHODS: Treated women were routinely recommended to have follow-up with annual smears for at least 5 years.

MAIN OUTCOME MEASURES: Using individually linked nationwide register data on conizations and follow-up tests (smears and biopsies), we calculated the cumulative proportion of treated women undergoing the recommended follow-up. We measured this cumulative proportion conservatively in 15-month intervals for 5 years.

RESULTS: Adherence to annual follow-up among 45,984 treated women decreased gradually. In total, 90% of these women obtained at least one smear in the first post-treatment year, but only 40% obtained the recommended tests for 5 years. Five-year adherence was substantially better outside the capital area, for example, the odds ratio for women from Jutland compared with women from the capital area was 1.70 (95% confidence interval 1.60-1.82).

CONCLUSIONS: Adherence to follow-up after conization was poor in Denmark. Our findings suggest that because of this poor adherence, recommendations for long-term annual follow-up after treatment of cervical intraepithelial neoplasia may not be highly effective. Shorter follow-up schedules using highly sensitive tests appear attractive.