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Original article
Risk of CIN2+ following a diagnosis of genital warts: a nationwide cohort study
  1. Maria Blomberg1,2,
  2. Christian Dehlendorff3,
  3. Susanne K. Kjaer1,4
  1. 1 Unit of Virus, Lifestyle and Genes, Danish Cancer Society Research Center, Copenhagen, Denmark
  2. 2 Department of Dermatology, Bispebjerg Hospital, Copenhagen, Denmark
  3. 3 Statistics, Bioinformatics and Registry, Danish Cancer Society Research Center, Copenhagen, Denmark
  4. 4 Juliane Marie Centre, Gynecologic Clinic, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
  1. Correspondence to Dr Maria Blomberg, Unit of Virus, Lifestyle and Genes, Danish Cancer Society Research Center, Copenhagen 2100, Denmark; maria{at}


Objectives Individuals with genital warts may be particularly susceptible to human papillomavirus since they have failed to clear the virus. Consequently, women with genital warts could be at increased risk of cervical dysplasia. In this cohort study we aimed to compare the incidence of cervical intraepithelial neoplasia grade 2 or worse (CIN2+) in women with a diagnosis of genital warts with that of the general female population without genital warts.

Methods Using the Danish nationwide population-based health data registers, we identified women between 15 and 45 years and followed them for diagnoses of CIN2+ from 1995 to 2006. Genital wart diagnoses were recorded from birth, and Cox regression with attained age as underlying scale was used to estimate age-dependent HRs for the risk of CIN2+ with genital warts as a time-varying exposure.

Results Among 918 609 women without genital warts and 32 218 women with genital warts, 30 209 and 1533 women, respectively, had a subsequent diagnosis of CIN2+. A significantly higher risk of CIN2+ was found among women with genital warts relative to those without (HR, 2.43; 95% CI 2.30 to 2.56). Treatment-resistant genital warts posed a significantly higher risk of CIN2+ than did transient genital warts (HR, 1.20; 95% CI 1.01 to 1.43). The risks remained elevated more than 4 years after the genital wart diagnosis.

Conclusion Clinicians should ensure that women with genital warts are screened for cervical cancer after the genital wart diagnosis and that they continue to be screened on time.

  • genital warts
  • cervical cytology
  • hpv
  • epidemiology (general)
  • anogenital cancer

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  • Handling editor Francesca Ceccherini Silberstein

  • Contributors The authors agree to be accountable for all aspects of this work. All authors have contributed substantially to the design of the work, acquisition, analysis and interpretation of data, and they have either drafted (MB) or critically revised the work (SKK, CD). All have approved the final version.

  • Funding This work was supported by funding from the Mermaid-2 project. The sponsor of the study had no role in study design, data collection, data analysis, data interpretation or writing of the report. The corresponding author had full access to all the data and had final responsibility for the decision to submit for publication.

  • Competing interests SKK has received speaker’s fee from Sanofi Pasteur, MSD and Merck, scientific advisory board fee from Merck, and research grant through her institution from Merck.

  • Patient consent for publication Not required.

  • Ethics approval The study was approved by the Danish Data Protection Agency (reference number 2014-41-2917).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.

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