Balancing diagnostic accuracy and cost in the follow-up of histological low-grade squamous intraepithelial lesions.

INTRODUCTION: Primary cervical screening with testing for human papillomavirus (HPV) brings increased detection of women with low-grade squamous intraepithelial lesion recommended for follow-up with colposcopy. This study evaluates whether co-testing (HPV + cytology) or testing for HPV alone can safely replace colposcopy as follow-up for histologically confirmed low-grade squamous intraepithelial lesions. It estimates these strategies' diagnostic performance in detecting histological high-grade squamous intraepithelial or more severe lesions at follow-up and analyzes their relative cost-effectiveness.

MATERIAL AND METHODS: This is a retrospective cohort study on follow-up data of women aged 23-70 with histological low-grade squamous intraepithelial lesion, diagnosed during 2017-2018, with an analysis of data from the Swedish National Cervical Screening Registry. Out of the 14 643 women with low-grade squamous intraepithelial lesions, 4213 women with complete data on HPV, cytology, and histology results were analyzed. The primary outcome was to estimate the diagnostic performance of the strategies of co-testing (HPV + cytology) and human papillomavirus-alone in detecting histological high-grade squamous intraepithelial or more severe lesions in the follow-up of histological low-grade squamous intraepithelial lesions. The secondary outcome was to perform a cost-effectiveness analysis of these strategies.

RESULTS: Using co-testing as the primary follow-up and reserving colposcopy for women who tested positive for HPV or cytology results yielded a sensitivity of 96% for high-grade squamous intraepithelial or more severe lesions. HPV-alone testing had 88% sensitivity. Adding colposcopy to co-testing would require 1735 (70%) additional examinations to detect 14 (3.9%) more women with high-grade squamous intraepithelial or more severe lesions. No cancer cases were missed by co-testing or HPV-alone. The cost of detecting one extra high-grade squamous intraepithelial or more severe lesion by adding colposcopy to co-testing was 81 959 EUR.

CONCLUSIONS: Histological low-grade squamous intraepithelial lesion follow-up can be safely managed with co-testing, considerably reducing the number of colposcopies and associated costs.