Background: The aim of this study was to assess the probability of low-grade squamous intra-epithelial lesion (LSIL) regression in young women, and to examine the factors associated with this regression.
Methods: In a longitudinal study of human papilloma virus (HPV) infection, female adolescents aged 13-22 years were examined every 4 months by cytology, colposcopy, and HPV DNA status. Both prevalent and incident LSIL cases were included in the analysis, with regression defined as at least three consecutive normal Pap smears.
Findings: Median follow-up time from baseline (defined as the time of first LSIL diagnosis) for the 187 women with LSIL was 61 months (IQR 34-80). Median time they had been sexually active at diagnosis was 3.2 years (2.6-6.5). Probability of regression for the entire cohort was 61% (95% CI 53-70) at 12 months and 91% (84-99) at 36 months of follow-up. No associations were found between LSIL regression and HPV status at baseline, sexual behaviour, contraceptive use, substance or cigarette use, incident sexually transmitted infection, or biopsy. Multivariate analysis showed that only HPV status at the current visit was associated with rate of regression, whether infection was caused by one or more viral types (relative hazard=0.3 [95% CI 0.21-0.42], and 0.14 [0.08-0.25], respectively).
Interpretation: The high rate of regression recorded in this study lends support to observation by cytology in the management of LSIL in female adolescents. Negative HPV status was associated with regression, suggesting that HPV testing could be helpful in monitoring LSIL.