Human papillomavirus and predictors of cervical intraepithelial neoplasia among young mothers in a prospective follow-up study.

OBJECTIVE

To study the incidence times and rates for cervical intraepithelial neoplasia (CIN) and its predictors.

MATERIAL AND METHODS

This is a prospective follow-up study at Turku University Hospital, Finland. The Finnish Family human papillomavirus (HPV) study comprised 329 pregnant women followed up for 3 years. In an extension of the follow-up period, 171 women participated in an additional 3 years follow-up. Cervical scrapings for HPV testing and cervical smears were collected at each follow-up visit (2, 12, 24 and 36 months and 6 years). Following two abnormal cervical smears, colposcopy with biopsies was done. The main outcome measures were actuarial and crude incidence times, incidence rates and predictors of incident CIN.

RESULTS

During the follow-up period, 10 women (3.2%) developed biopsy-confirmed CIN, and four presented with incident atypical squamous cells suggesting high-grade squamous intraepithelial lesion cytology. The CIN/squamous intraepithelial lesion developed in 74.5 and 66.3 months, with crude incidence rates of 13.4/1,000 and 15.1/1,000 women months at risk, respectively. In multivariate Poisson regression, independent predictors of incident CIN were as follows: high-risk HPV positive at baseline (incidence rate ratio = 5.54; 95% confidence interval 1.02-30.14, p= 0.048); type-specific high-risk HPV persistence during follow-up (incidence rate ratio = 5.84; 95% confidence interval 2.28-17.93, p= 0.0001); cervical smear cytologically diagnosed for atypical squamous cells of undetermined significance or worse at any follow-up visit (incidence rate ratio = 4.56; 95% confidence interval 2.37-8.78, p= 0.0001); and new sexual partner during follow-up (incidence rate ratio = 9.45; 95% confidence interval 1.90-46.97, p= 0.006).

CONCLUSION

The results indicate that combined use of cervical smear and HPV testing, with prompt referral to colposcopy, enables accurate detection of incident CIN well before progression to invasive cancer. In addition to baseline and persistent high-risk HPV, abnormal cervical smear and new sexual partner are key predictors of incident CIN.